drm/xe/uapi: Change rsvd to pad in struct drm_xe_class_instance

Change rsvd to pad in struct drm_xe_class_instance to prevent the field
from being used in future.

v2: Change from fixup to regular commit because this touches the
    uAPI (Francois Dugast)
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_query.c

@@ -215,7 +215,10 @@ static int query_engines(struct xe_device *xe,
 				xe_to_user_engine_class[hwe->class];
 			hw_engine_info[i].engine_instance =
 				hwe->logical_instance;
-			hw_engine_info[i++].gt_id = gt->info.id;
+			hw_engine_info[i].gt_id = gt->info.id;
+			hw_engine_info[i].pad = 0;
+
+			i++;
 		}
 
 	if (copy_to_user(query_ptr, hw_engine_info, size)) {

include/uapi/drm/xe_drm.h

@@ -141,7 +141,8 @@ struct drm_xe_engine_class_instance {
 
 	__u16 engine_instance;
 	__u16 gt_id;
-	__u16 rsvd;
+	/** @pad: MBZ */
+	__u16 pad;
 };
 
 /**