igb: Add new feature Media Auto Sense for 82580 devices only

This patch adds support for the hardware feature Media Auto Sense.  This
feature requires a custom EEPROM image provided by our customer support
team.  The feature allows hardware designed with dual PHY's, fiber and
copper to be used with either media without additional EEPROM changes.
Fiber is preferred and driver will swap and configure for fiber media if
sensed by the device at any time. Device will swap back to copper if it
is the only media detected.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>