ixgbe: Add 1000Base-T device based on X550EM_X MAC

ixgbe: Add 1000Base-T device based on X550EM_X MAC

Add support for new 1000Base-T device based on X550EM_X MAC
type. All PHY operations are disabled as the PHY is controlled
by FW.

Signed-off-by: Paul Greenwalt <paul.greenwalt@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26242766
(cherry picked from commit 8dc963e1cd245e67d6a9ffb8447fc88fb6eaa370)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>