zink: handle shader io vars more generically for use with gs

geometry shaders have more inputs and use a lot of the same codepaths as
vertex shaders, so these changes add the inputs and remove checks for vertex-only
shaders

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7139>
1 file changed