intel/blorp: Set uses_sample_shading for MSAA blit shaders

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14020>

src/intel/blorp/blorp_blit.c

@@ -84,6 +84,7 @@ blorp_blit_get_frag_coords(nir_builder *b,
       coord = nir_isub(b, coord, nir_load_var(b, v->v_dst_offset));
 
    if (key->persample_msaa_dispatch) {
+      b->shader->info.fs.uses_sample_shading = true;
       return nir_vec3(b, nir_channel(b, coord, 0), nir_channel(b, coord, 1),
                       nir_load_sample_id(b));
    } else {