r8169: fix sleeping while holding spinlock.

As device_set_wakeup_enable can now sleep, move the call to outside
the critical section.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>