drm/sched: fix kernel-doc in gpu_scheduler.h

Fix following warning:
gpu_scheduler.h:103: warning: Function parameter or member 'priority' not described in 'drm_sched_entity'
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Nirmoy Das <nirmoy.das@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200328132025.19910-4-sam@ravnborg.org

include/drm/gpu_scheduler.h

@@ -56,6 +56,7 @@ enum drm_sched_priority {
  *              Jobs from this entity can be scheduled on any scheduler
  *              on this list.
  * @num_sched_list: number of drm_gpu_schedulers in the sched_list.
+ * @priority: priority of the entity
  * @rq_lock: lock to modify the runqueue to which this entity belongs.
  * @job_queue: the list of jobs of this entity.
  * @fence_seq: a linearly increasing seqno incremented with each