tg3: Do not call device_set_wakeup_enable() under spin_lock_bh

The tg3 driver calls device_set_wakeup_enable() under spin_lock_bh,
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
spin_lock_bh-protected area.

Reported-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>