radeonsi: fix random PS wave size

Fixes: b3b2f97f2e "radeonsi: add Wave32 heuristics and shader profiles"

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17410>

src/gallium/drivers/radeonsi/si_state_shaders.cpp

@@ -124,7 +124,7 @@ unsigned si_determine_wave_size(struct si_screen *sscreen, struct si_shader *sha
    /* TODO: Merged shaders must use the same wave size because the driver doesn't recompile
     * individual shaders of merged shaders to match the wave size between them.
     */
-   bool merged_shader = shader && !shader->is_gs_copy_shader &&
+   bool merged_shader = stage <= MESA_SHADER_GEOMETRY && shader && !shader->is_gs_copy_shader &&
                         (shader->key.ge.as_ls || shader->key.ge.as_es ||
                          stage == MESA_SHADER_TESS_CTRL || stage == MESA_SHADER_GEOMETRY);