[media] au8522_decoder: remove obsolete control ops

Now that au0828 has been converted to the control framework these
compatilibity ops are no longer needed.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>