[PATCH] v4l use-after-free fix

From: Greg KH <greg@kroah.com>

When working on converting the usb v4l drivers to the new v4l class
changes, I ran into this nasty bug.  Seems that the core was using a
structure after it had been freed.  The patch below fixes it.

drivers/media/video/videodev.c

@@ -349,9 +349,9 @@ void video_unregister_device(struct video_device *vfd)
 	if(video_device[vfd->minor]!=vfd)
 		panic("videodev: bad unregister");
 
-	class_device_unregister(&vfd->class_dev);
 	devfs_remove(vfd->devfs_name);
 	video_device[vfd->minor]=NULL;
+	class_device_unregister(&vfd->class_dev);
 	up(&videodev_lock);
 }