media: videobuf2-v4l2: remove redundant error test

request_fd is validated under media_request_get_by_fd() just below this
check. Thus remove it.
Suggested-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/common/videobuf2/videobuf2-v4l2.c

@@ -488,11 +488,6 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
 		    !q->ops->buf_out_validate))
 		return -EINVAL;
 
-	if (b->request_fd < 0) {
-		dprintk(q, 1, "%s: request_fd < 0\n", opname);
-		return -EINVAL;
-	}
-
 	req = media_request_get_by_fd(mdev, b->request_fd);
 	if (IS_ERR(req)) {
 		dprintk(q, 1, "%s: invalid request_fd\n", opname);