[media] sur40: fix occasional oopses on device close

Closing the V4L2 device sometimes triggers a kernel oops.
Present patch fixes this.
Signed-off-by: Martin Kaltenbrunner <modin@yuri.at>
Signed-off-by: Florian Echtler <floe@butterbrot.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: <stable@vger.kernel.org>      # for v4.2 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/input/touchscreen/sur40.c

@@ -447,7 +447,7 @@ static void sur40_process_video(struct sur40_state *sur40)
 
 	/* return error if streaming was stopped in the meantime */
 	if (sur40->sequence == -1)
-		goto err_poll;
+		return;
 
 	/* mark as finished */
 	new_buf->vb.vb2_buf.timestamp = ktime_get_ns();
@@ -725,6 +725,7 @@ static int sur40_start_streaming(struct vb2_queue *vq, unsigned int count)
 static void sur40_stop_streaming(struct vb2_queue *vq)
 {
 	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
+	vb2_wait_for_all_buffers(vq);
 	sur40->sequence = -1;
 
 	/* Release all active buffers */