nir: Delete lower_io_types

It's only used by the ir3 stand-alone compiler and Rob said we could
delete it.

Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/meson.build

@@ -128,7 +128,6 @@ files_libnir = files(
   'nir_lower_io_arrays_to_elements.c',
   'nir_lower_io_to_temporaries.c',
   'nir_lower_io_to_scalar.c',
-  'nir_lower_io_types.c',
   'nir_lower_packing.c',
   'nir_lower_passthrough_edgeflags.c',
   'nir_lower_patch_vertices.c',