nir: Remove old-school deref chain support

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/nir_lower_tex.c

@@ -882,8 +882,6 @@ nir_lower_tex(nir_shader *shader, const nir_lower_tex_options *options)
 {
    bool progress = false;
 
-   nir_assert_unlowered_derefs(shader, nir_lower_texture_derefs);
-
    nir_foreach_function(function, shader) {
       if (function->impl)
          progress |= nir_lower_tex_impl(function->impl, options);