ixgbe: Fix get_supported_physical_layer() due to new 82599 PHY types

A purely cosmetic change.  Report which physical layer is present, instead
of PHY unknown.  82599 added new PHY types for the SFP+ devices, and this
was missed getting updated.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>