zink: add helper for vec-type input variables in ntv

we'll see a lot of reuse of this type of thing, so we can avoid duplicating
it later

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7192>
1 file changed