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/glsl/gl_nir_lower_atomics.c

@@ -142,8 +142,6 @@ gl_nir_lower_atomics(nir_shader *shader,
 {
    bool progress = false;
 
-   nir_assert_unlowered_derefs(shader, nir_lower_atomic_counter_derefs);
-
    nir_foreach_function(function, shader) {
       if (!function->impl)
          continue;

src/compiler/glsl/gl_nir_lower_samplers.c

@@ -173,8 +173,6 @@ gl_nir_lower_samplers(nir_shader *shader,
 {
    bool progress = false;
 
-   nir_assert_unlowered_derefs(shader, nir_lower_texture_derefs);
-
    nir_foreach_function(function, shader) {
       if (function->impl)
          progress |= lower_impl(function->impl, shader_program);

src/compiler/glsl/gl_nir_lower_samplers_as_deref.c

@@ -282,8 +282,6 @@ gl_nir_lower_samplers_as_deref(nir_shader *shader,
    bool progress = false;
    struct lower_samplers_as_deref_state state;
 
-   nir_assert_unlowered_derefs(shader, nir_lower_texture_derefs);
-
    state.shader = shader;
    state.shader_program = shader_program;
    state.remap_table = _mesa_hash_table_create(NULL, _mesa_key_hash_string,