[media] Fix double free of video_device in mem2mem_testdev

video_device is already being freed in video_device.release callback on
release.
Signed-off-by: Pawel Osciak <pawel@osciak.com>
Reported-by: Roland Kletzing <devzero@web.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/mem2mem_testdev.c

@@ -1011,7 +1011,6 @@ 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);