gianfar: Check if phydev present on ethtool -A

gianfar: Check if phydev present on ethtool -A

commit 98a46d46d1bc983125b6ff9a0e831050a7011713 upstream.

This fixes a seg fault on 'ethtool -A' entry if the
interface is down.  Obviously we need to have the
phy device initialized / "connected" (see of_phy_connect())
to be able to advertise pause frame capabilities.

Fixes: 23402bddf9e56eecb27bbd1e5467b3b79b3dbe58
Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>