drm/nouveau/gsp/r535: add support for rm control

Adds the plumbing to start making RM control calls, and initialises
objects to represent internal RM objects provided to us during init.

These will be used by subsequent patches.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230918202149.4343-34-skeggsb@gmail.com