panfrost: Move checksum routines to root panfrost

These are Gallium-independent and clean code; as is tradition, let's
hoist them up out of the Gallium driver as a bit of yak shaving as we
prepare to untangle the monster that is pan_resource.c

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>
7 files changed