d3d12: use nir_metadata_none instead of its value

Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12324>

src/gallium/drivers/d3d12/d3d12_nir_passes.c

@@ -736,7 +736,7 @@ d3d12_lower_primitive_id(nir_shader *shader)
       }
    }
 
-   nir_metadata_preserve(impl, 0);
+   nir_metadata_preserve(impl, nir_metadata_none);
 }
 
 static void
@@ -875,6 +875,6 @@ d3d12_lower_triangle_strip(nir_shader *shader)
       }
    }
 
-   nir_metadata_preserve(impl, 0);
+   nir_metadata_preserve(impl, nir_metadata_none);
    NIR_PASS_V(shader, nir_lower_var_copies);
 }