Supported speeds is not updated when SFP is removed or replaced

Supported speed is obtained from lmt field in READ_CONFIG mailbox
response. Driver updates supported speeds only once from PCI probe
path. After that it is never updated. So, supported speeds remains the
same till reboot or driver reload.

When SFP is removed or inserted, driver gets SLI-Port Event ACQE.  If
SFP is removed, lmt wil have value 0. If a different SFP is inserted,
lmt will have value according to its supported speeds.  So, afterr
SLI-Port Event ACQE handling path, send READ_CONFIG mailbox and update
supported speeds. If READ_CONFIG fails, set supported speeds to
unknown and log.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>