gianfar: ethernet vanishes after restoring from hibernation

If a gianfar ethernet device is down prior to hibernating a
system, it will no longer be present upon system restore.

For example:

	~# ifconfig eth0 down
	~# echo disk > /sys/power/state

	  <trigger a restore from hibernation>

	~# ifconfig eth0 up
	SIOCSIFFLAGS: No such device

This happens because the restore function bails out early upon
finding devices that were not up at hibernation.  In doing so,
it never gets to the netif_device_attach call at the end of
the restore function.  Adding the netif_device_attach as done
here also makes the gfar_restore code consistent with what is
done in the gfar_resume code.

Cc: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>