[media] [RFC] radio-mr800: locking fixes

- serialize the suspend and resume functions using the global lock.
- do not call usb_autopm_put_interface after a disconnect.
- fix a race when disconnecting the device.

Reported-by: David Ellingsworth <david@identd.dyndns.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: David <Ellingsworth&lt;david@identd.dyndns.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>