minigbm: update virgl_hw.h

Taken from ToT virglrenderer (commit e27247), which contains the
upstream version of this file.

BUG=b:132939420
TEST=compile

Change-Id: I6efc5faa55dfc2841ca17d04db9f16eaeac39d7e
Reviewed-on: https://chromium-review.googlesource.com/1645878
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Lepton Wu <lepton@chromium.org>
1 file changed