st/mesa: start adding support for hw atomics atom. (v2)

st/mesa: start adding support for hw atomics atom. (v2)

This adds a new atom that calls the new driver API to
bind buffers containing hw atomics.

v2: fixup bindings for sparse buffers. (mareko/nha)
don't bind buffer atomics when hw atomics are enabled.
use NewAtomicBuffer (mareko)

Tested-By: Gert Wollny <gw.fossdev@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>