net: txgbe: Support phylink MAC layer

Add phylink support to Wangxun 10Gb Ethernet controller for the 10GBASE-R
interface.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>