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.

Reference OA:
https://patchwork.freedesktop.org/patch/558362/?series=121084&rev=6



v2: Reduce reserved[] to 3 u64 (Matthew Brost)

Cc: Francois Dugast <francois.dugast@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
[Rodrigo Rebased]
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>