o "min_tx_rate" option has been added for minimum Tx rate. Hence, for
  consistent naming, "max_tx_rate" option has been introduced for maximum
  Tx rate.

o Change in v2: "rate" can be used along with "max_tx_rate".
  When both are specified, "max_tx_rate" should override.

o Change in v3:
  * IFLA_VF_RATE: When IFLA_VF_RATE is used, and user has given only one of
    min_tx_rate or max_tx_rate, reading of previous rate limits is done in
    userspace instead of in kernel space before ndo_set_vf_rate.

  * IFLA_VF_TX_RATE: When IFLA_VF_TX_RATE is used, min_tx_rate is always read
    in kernel space. This takes care of below scenarios:
    (1) when old tool sends "rate" but kernel is new (expects min and max)
    (2) when new tool sends only "rate" but kernel is old (expects only "rate")

o Change in v4 as suggested by Stephen Hemminger:
  * As per iproute policy, input and output formats should match. Changing display
    of max_tx_rate and min_tx_rate options accordingly.
	./ip/ip link show p3p1
	8: p3p1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
        link/ether 00:0e:1e:16:ce:40 brd ff:ff:ff:ff:ff:ff
        vf 0 MAC 2a:18:8f:4d:3d:d4, tx rate 700 (Mbps), max_tx_rate 700Mbps, min_tx_rate 200Mbps
        vf 1 MAC 72:dc:ba:f9:df:fd
Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>