radeonsi: move as_ls/es/ngg setting out of si_shader_selector_key

radeonsi: move as_ls/es/ngg setting out of si_shader_selector_key

Do it when we bind shaders.

The advantages are:
- no need to memset the fields when any shader variant state is changed
  (e.g. culling on/off)
- no need to recompute the fields every time that happens

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12656>