minigbm: i915: use experimental uapi

minigbm: i915: use experimental uapi

New proposed i915 features for testing purposes.

BUG=b:153111783,b:155511259
TEST=Protected playback works w/ associated Chrome OS changes

Change-Id: I67bb178794d827c85667bff2fb4500c69fe0a4e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/2459531
Reviewed-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Jeffrey Kardatzke <jkardatzke@google.com>
Commit-Queue: Gurchetan Singh <gurchetansingh@chromium.org>