net: atlantic: A2: EEE support

This patch adds EEE support on A2.

Signed-off-by: Nikita Danilov <ndanilov@marvell.com>
Co-developed-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>