ixgbe: Display currently attached PHY through ethtool

This patch extends the ethtool interface to display what PHY
is currently connected to a NIC.  The results can be viewed in
ethtool ethX output.

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>