nir: Get rid of nir_shader::stage

It's redundant with nir_shader::info::stage.

Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

src/compiler/nir/nir_lower_bitmap.c

@@ -133,7 +133,7 @@ void
 nir_lower_bitmap(nir_shader *shader,
                  const nir_lower_bitmap_options *options)
 {
-   assert(shader->stage == MESA_SHADER_FRAGMENT);
+   assert(shader->info.stage == MESA_SHADER_FRAGMENT);
 
    lower_bitmap_impl(nir_shader_get_entrypoint(shader), options);
 }