nir/lower_io: Add support for lowering deref_mode_is

The guts are still missing so it will blow up if it sees any
deref_mode_is intrinsic that it can't constant-fold from the mode.

Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6332>

src/compiler/nir/nir_validate.c

@@ -671,6 +671,7 @@ validate_intrinsic_instr(nir_intrinsic_instr *instr, validate_state *state)
       break;
 
    case nir_intrinsic_deref_mode_is:
+   case nir_intrinsic_addr_mode_is:
       validate_assert(state,
          util_bitcount(nir_intrinsic_memory_modes(instr)) == 1);
       break;