net: phy: marvell: provide genphy suspend/resume

Marvell PHYs support generic PHY suspend/resume, so provide those
callbacks to all marvell specific drivers.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>