2u cpsw hardware on K2G uses rgmii link to interface with Phy. So add
support for this interface in the code so that driver can be re-used
for 2u hardware.
Signed-off-by: NMurali Karicheri <m-karicheri2@ti.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>