Added support for 1000BASE-BX, i.e. Gigabit Ethernet over single strand
of single-mode fiber.
The initialization of a 1000BASE-BX SFP is the same as 1000BASE-SX/LX
with the only difference that the Bit Rate Nominal Value must be
checked to make sure it is a Gigabit Ethernet transceiver, as described
by the SFF-8472 specification.

This was tested with the FS.com SFP-GE-BX 1310/1490nm 10km transceiver:
$ ethtool -m eth4
        Identifier                                : 0x03 (SFP)
        Extended identifier                       : 0x04 (GBIC/SFP defined by 2-wire interface ID)
        Connector                                 : 0x07 (LC)
        Transceiver codes                         : 0x00 0x00 0x00 0x40 0x00 0x00 0x00 0x00 0x00
        Transceiver type                          : Ethernet: BASE-BX10
        Encoding                                  : 0x01 (8B/10B)
        BR, Nominal                               : 1300MBd
        Rate identifier                           : 0x00 (unspecified)
        Length (SMF,km)                           : 10km
        Length (SMF)                              : 10000m
        Length (50um)                             : 0m
        Length (62.5um)                           : 0m
        Length (Copper)                           : 0m
        Length (OM3)                              : 0m
        Laser wavelength                          : 1310nm
        Vendor name                               : FS
        Vendor OUI                                : 64:9d:99
        Vendor PN                                 : SFP-GE-BX
        Vendor rev                                :
        Option values                             : 0x20 0x0a
        Option                                    : RX_LOS implemented
        Option                                    : TX_FAULT implemented
        Option                                    : Power level 3 requirement
        BR margin, max                            : 0%
        BR margin, min                            : 0%
        Vendor SN                                 : S2202359108
        Date code                                 : 220307
        Optical diagnostics support               : Yes
        Laser bias current                        : 17.650 mA
        Laser output power                        : 0.2132 mW / -6.71 dBm
        Receiver signal average optical power     : 0.2740 mW / -5.62 dBm
        Module temperature                        : 47.30 degrees C / 117.13 degrees F
        Module voltage                            : 3.2576 V
        Alarm/warning flags implemented           : Yes
        Laser bias current high alarm             : Off
        Laser bias current low alarm              : Off
        Laser bias current high warning           : Off
        Laser bias current low warning            : Off
        Laser output power high alarm             : Off
        Laser output power low alarm              : Off
        Laser output power high warning           : Off
        Laser output power low warning            : Off
        Module temperature high alarm             : Off
        Module temperature low alarm              : Off
        Module temperature high warning           : Off
        Module temperature low warning            : Off
        Module voltage high alarm                 : Off
        Module voltage low alarm                  : Off
        Module voltage high warning               : Off
        Module voltage low warning                : Off
        Laser rx power high alarm                 : Off
        Laser rx power low alarm                  : Off
        Laser rx power high warning               : Off
        Laser rx power low warning                : Off
        Laser bias current high alarm threshold   : 110.000 mA
        Laser bias current low alarm threshold    : 1.000 mA
        Laser bias current high warning threshold : 100.000 mA
        Laser bias current low warning threshold  : 1.000 mA
        Laser output power high alarm threshold   : 0.7079 mW / -1.50 dBm
        Laser output power low alarm threshold    : 0.0891 mW / -10.50 dBm
        Laser output power high warning threshold : 0.6310 mW / -2.00 dBm
        Laser output power low warning threshold  : 0.1000 mW / -10.00 dBm
        Module temperature high alarm threshold   : 90.00 degrees C / 194.00 degrees F
        Module temperature low alarm threshold    : -45.00 degrees C / -49.00 degrees F
        Module temperature high warning threshold : 85.00 degrees C / 185.00 degrees F
        Module temperature low warning threshold  : -40.00 degrees C / -40.00 degrees F
        Module voltage high alarm threshold       : 3.7950 V
        Module voltage low alarm threshold        : 2.8050 V
        Module voltage high warning threshold     : 3.4650 V
        Module voltage low warning threshold      : 3.1350 V
        Laser rx power high alarm threshold       : 0.7079 mW / -1.50 dBm
        Laser rx power low alarm threshold        : 0.0028 mW / -25.53 dBm
        Laser rx power high warning threshold     : 0.6310 mW / -2.00 dBm
        Laser rx power low warning threshold      : 0.0032 mW / -24.95 dBm
Signed-off-by: Ernesto Castellotti <ernesto@castellotti.net>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20240301184806.2634508-3-anthony.l.nguyen@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>