radeonsi: don't use info.gs.invocations if it's not GS

It's a union, which makes gs.invocations undefined for VS and TES.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16885>
1 file changed