radeonsi: write VS/TES system values into LDS after culling

The system values are written into LDS after the new thread ID is known,
so it removes pointer indirection with the old thread ID.

Also, the LDS stores are skipped entirely if vertices are culled.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7172>
1 file changed