[media] drivers/media/video/au0828/au0828-video.c: add missing video_device_release

At the point of the call to video_register_device, both dev->vbi_dev and
dev->vdev have been allocated, and so should be freed on failure.  The
error-handling code is moved to the end of the function, to avoid code
duplication.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>