[SUNGEM]: Marvell PHY suspend.

In a short discussion with Benjamin Herrenschmidt he mentioned
that Marvell PHYs are powered down the same way as the other
ones we currently handle. Thus actually do that, hopefully
saving some power during suspend.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David S. Miller <davem@davemloft.net>