panfrost: Move pan_afbc.c to root

Now that PIPE formats are shared across Mesa, this well-documented piece
of code is a good fit for root panfrost, let's move it and get a little
closer to taming the mess of resources.

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/3858>
5 files changed