V4L/DVB: v4l: mem2mem_testdev: add missing release for video_device

Video device was not being released on driver remove.
Signed-off-by: NPawel Osciak <p.osciak@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/mem2mem_testdev.c

@@ -1014,6 +1014,7 @@ static int m2mtest_remove(struct platform_device *pdev)
 	v4l2_m2m_release(dev->m2m_dev);
 	del_timer_sync(&dev->timer);
 	video_unregister_device(dev->vfd);
+	video_device_release(dev->vfd);
 	v4l2_device_unregister(&dev->v4l2_dev);
 	kfree(dev);