V4L/DVB (13553): v4l: Use the video_is_registered function in device drivers

Fix all device drivers to use the video_is_registered function instead
of checking video_device::minor.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/ov511.c b/drivers/media/video/ov511.c
index 0bc2cf5..b636160 100644
--- a/drivers/media/video/ov511.c
+++ b/drivers/media/video/ov511.c
@@ -5884,7 +5884,7 @@
 
 error:
 	if (ov->vdev) {
-		if (-1 == ov->vdev->minor)
+		if (!video_is_registered(ov->vdev))
 			video_device_release(ov->vdev);
 		else
 			video_unregister_device(ov->vdev);