Define get/set phy tunable callbacks in ethtool ops.
This will allow MAC drivers with integrated PHY still to implement
these tunables.
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NIgor Russkikh <irusskikh@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>