This is a preparation commit to add support for new variants of the
decoder.
The functions will later be shared with vdpu381 (rk3588) and vdpu383
(rk3576).
Tested-by: Diederik de Haas <didi.debian@cknow.org> # Rock 5B Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>