pan/bi: Split special class in two

Some special instructions are scheduled on the FMA unit, let's add a
new class for this case and rename the old one accordingly.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7408>
8 files changed