intel/compiler: lower bit sizes in NIR postprocessing

It appears that between preprocess & postprocess some descriptor
lowering introduces 8bit types in the shader, so run the lower bit
size again to make sure we don't have any unsupported types in our
shader.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: e06144a818 ("anv: Use 64bit_global_32bit_offset for SSBOs")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4478
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9705>

src/intel/compiler/brw_nir.c

@@ -1083,6 +1083,8 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
 
    UNUSED bool progress; /* Written by OPT */
 
+   OPT(nir_lower_bit_size, lower_bit_size_callback, (void *)compiler);
+
    OPT(brw_nir_lower_scoped_barriers);
    OPT(nir_opt_combine_memory_barriers, combine_all_barriers, NULL);