radeonsi: replace llvm based fixed tcs with nir

radeonsi: replace llvm based fixed tcs with nir

Create nir passthrough shader with explicit input/output and vertex
output count so that it can be handled by compiler same as user tcs.

The drawback is we create more si_shader_selector with different
input/output and vertex output count which was handled by compiler
backend before.

As fixed function tcs can be handled like user tcs, we don't need
the dedicated fixed_func_tcs_shader state either.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16705>