net: netcp: ethss: re-use stats handling code for 2u hardware

The stats block in 2u cpsw hardware is similar to the one on nu
and hence handle it in a similar way by using a macro that includes
2u hardware as well.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>