drm/nouveau/fifo: add common runlist/engine topology

Creates an nvkm_runl for each runlist on the GPU, and an nvkm_engn for
each engine that is reachable from a runlist.

- basically what gk104- already does, but extended to all chips
- adds per-runlist CHID allocators (Ampere)
- splits g98/gt2xx out from g84 (different target engines)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>