media: uvcvideo: Fix deadlock during uvc_probe

If uvc_probe() fails, it can end up calling uvc_status_unregister() before
uvc_status_init() is called.

Fix this by checking if dev->status is NULL or not in
uvc_status_unregister().

Reported-by:  <syzbot+9446d5e0d25571e6a212@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/linux-media/20241020160249.GD7770@pendragon.ideasonboard.com/T/#m506744621d72a2ace5dd2ab64055be9898112dbd


Fixes: c5fe3ed6 ("media: uvcvideo: Avoid race condition during unregister")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20241022-race-unreg-v1-1-2212f364d9de@chromium.org


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>