gianfar: Do not call device_set_wakeup_enable() under a spinlock

The gianfar driver calls device_set_wakeup_enable() under a spinlock,
which causes a problem to happen after the recent core power
management changes, because this function can sleep now.  Fix this
by moving the device_set_wakeup_enable() call out of the
spinlock-protected area.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>