media: rkvdec: Move cabac tables to their own source file
This is in preparation to add support for new variants that will use the
same tables.
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>