panfrost: Pack invocation_shifts manually instead of a bit field

gcc generates exceptionally bad code for panfrost_pack_work_groups_fused
otherwise ... although that routine is somehow still hot ...

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3067>
3 files changed