pan/bi: Make bi_writemask take a destination

pan/bi: Make bi_writemask take a destination

Assuming it's only the first destination breaks assumptions across the
compiler. Add a destination source and fix up the many corresponding
issues. Nothing to backport as far as I understand since multidest
instruction are new.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9164>