ixgbe: set media type for 82599 T3 LOM

The media type was not being set for the 82599 T3 LAN on motherboard.  This
change corrects that.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>