media: rkvdec: Use structs to represent the HW RPS

media: rkvdec: Use structs to represent the HW RPS

This is in preparation to add support for other variants of the decoder.

Moving to struct representation is mainly to prepare for multicore
support that is present in e.g. rk3588.

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>