radv: use shared ac_ngg_compute_subgroup_info

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12496

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35473>
4 files changed