In order for igb to support MDI setting support via
ethtool this code is needed to allow setting the MDI state
via software.

This is in regards to the related ethtool patch
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Aaron Brown aaron.f.brown@intel.com
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>