tgsi/scan: add hw atomic to the list of memory accessing files

This fixes 4 out of 5 cases in:
arb_framebuffer_no_attachments-atomic on cayman.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Cc: "18.0 18.1" <mesa-stable@lists.freedesktop.org>
(cherry picked from commit f2f464de)