drm/amdgpu: Use DRM scheduler API in amdgpu_xcp_release_sched

Lets use the existing helper instead of peeking into the structure
directly.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Tvrtko Ursulin

drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c

@@ -427,7 +427,7 @@ void amdgpu_xcp_release_sched(struct amdgpu_device *adev,
 		return;
 
 	sched = entity->entity.rq->sched;
-	if (sched->ready) {
+	if (drm_sched_wqueue_ready(sched)) {
 		ring = to_amdgpu_ring(entity->entity.rq->sched);
 		atomic_dec(&adev->xcp_mgr->xcp[ring->xcp_id].ref_cnt);
 	}