Also adds some comments to vk_format_utils.h. Bug: angleproject:3372 Change-Id: I529b9b189e4cdfd400c3c981a47139727d9954ab Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1565062 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>
