media: vim2m: use cancel_delayed_work_sync instead of flush_schedule_work

The use of flush_schedule_work() made no sense and caused a syzkaller error.
Replace with the correct cancel_delayed_work_sync().
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: syzbot+69780d144754b8071f4b@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>      # for v4.20 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/vim2m.c

@@ -803,10 +803,11 @@ static int vim2m_start_streaming(struct vb2_queue *q, unsigned count)
 static void vim2m_stop_streaming(struct vb2_queue *q)
 {
 	struct vim2m_ctx *ctx = vb2_get_drv_priv(q);
+	struct vim2m_dev *dev = ctx->dev;
 	struct vb2_v4l2_buffer *vbuf;
 	unsigned long flags;
 
-	flush_scheduled_work();
+	cancel_delayed_work_sync(&dev->work_run);
 	for (;;) {
 		if (V4L2_TYPE_IS_OUTPUT(q->type))
 			vbuf = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);