ixgbe: add a callback to set the maximum transmit bitrate

ixgbe: add a callback to set the maximum transmit bitrate

Orabug: 23177316

This commit adds a callback which allows to adjust the maximum transmit
bitrate the card can output. This makes it possible to get a smooth
traffic instead of the default burst-y behaviour when trying to output
e.g. a video stream.

Much of the logic needed to get a correct bcnrc_val was taken from the
ixgbe_set_vf_rate_limit() function.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit c04f90e592431489df114971ff025265d429e48f)
Signed-off-by: Brian Maly <brian.maly@oracle.com>