[media] uvcvideo: Remove buffers from the queues when freeing

When freeing memory for the video buffers also remove them from the
irq & main queues.

This fixes an oops when doing the following:

open ("/dev/video", ..)
VIDIOC_REQBUFS
VIDIOC_QBUF
VIDIOC_REQBUFS
close ()

As the second VIDIOC_REQBUFS will cause the list entries of the buffers
to be cleared while they still hang around on the main and irc queues

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/uvc/uvc_queue.c

@@ -104,6 +104,8 @@ static int __uvc_free_buffers(struct uvc_video_queue *queue)
 	}
 
 	if (queue->count) {
+		uvc_queue_cancel(queue, 0);
+		INIT_LIST_HEAD(&queue->mainqueue);
 		vfree(queue->mem);
 		queue->count = 0;
 	}