drm/xe: Make DRM_XE_DEVICE_QUERY_ENGINES future proof
We have at least 2 future features(OA and future media engines
capabilities) that will require Xe to provide more information about
engines to UMDs.
But this information should not just be added to
drm_xe_engine_class_instance for a couple of reasons:
- drm_xe_engine_class_instance is used as input to other structs/uAPIs
and those uAPIs don't care about any of these future new engine fields
- those new fields are useless information after initialization for
some UMDs, so it should not need to carry that around
So here my proposal is to make DRM_XE_DEVICE_QUERY_ENGINES return an
array of drm_xe_query_engine_info that contain
drm_xe_engine_class_instance and 3 u64s to be used for future features.