intel: Always call nir_lower_frexp.

We have NIR lowering for Vulkan, and rely on GLSL's lowering in the
frontend, but this will let us drop the GLSL lowering.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22083>

src/intel/compiler/brw_nir.c

@@ -930,6 +930,8 @@ brw_preprocess_nir(const struct brw_compiler *compiler, nir_shader *nir,
 
    nir_validate_ssa_dominance(nir, "before brw_preprocess_nir");
 
+   OPT(nir_lower_frexp);
+
    if (is_scalar) {
       OPT(nir_lower_alu_to_scalar, NULL, NULL);
    }