asahi: decode: Add a params argument to pass through

asahi: decode: Add a params argument to pass through

Sooner or later we were going to need divergent codepaths in decode, and
it looks like now is the time. Add a `params` typedef and pass it
through all the decoder callbacks. This is an alias for
drm_asahi_params_global, but use a typedef so we can change that later
without changing dozens of instances.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24258>