radeonsi: simplify the NGG culling condition in si_draw_vbo

radeonsi: simplify the NGG culling condition in si_draw_vbo

Changes:

- disallow NGG culling for GS, fast launch for tess using template args
  (GS can't do NGG culling, tess can't do fast launch)

- skip checking current_rast_prim with tessellation
  (bake the condition into ngg_cull_vert_threshold)

- use only 1 vertex count threshold for enabling NGG shader culling
  to simplify it. I think it doesn't have a big impact. The threshold
  computation depends on more parameters than just fast launch.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8434>