nir: Allow to skip integer ops in nir_lower_to_source_mods

Some hardware supports source mods only for float operations. Make it
possible to skip lowering to source mods in these cases.

v2: use option flags instead of a boolean (Jason Ekstrand)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/compiler/brw_nir.c

@@ -796,7 +796,7 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
 
    OPT(nir_opt_algebraic_late);
 
-   OPT(nir_lower_to_source_mods);
+   OPT(nir_lower_to_source_mods, nir_lower_all_source_mods);
    OPT(nir_copy_prop);
    OPT(nir_opt_dce);
    OPT(nir_opt_move_comparisons);