net: phy: added ethtool master-slave configuration support

To configure the T1 phy as master or slave using the ethtool -s <dev>
master-slave <forced-master/forced-slave>, the config_aneg and read
status functions are added.

Signed-off-by: Prasanna Vengateshan <prasanna.vengateshan@microchip.com>
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>