ixgbe: Correct X550 phy ID

We were using an old Alpha version of the X550 phy ID.  This was leading
to unnecessary queries of the PHY.  I removed the old ID (which shouldn't
be on any HW) and add the two that are.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>