drm/amdgpu: add sched sync for amdgpu job v2

this is an improvement for previous patch, the sched_sync is to store fence
that could be skipped as scheduled, when job is executed, we didn't need
pipeline_sync if all fences in sched_sync are signalled, otherwise insert
pipeline_sync still.

v2: handle error when adding fence to sync failed.

Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com> (v1)
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index ea8ad69..37bd003 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1124,6 +1124,7 @@ struct amdgpu_job {
 	struct amdgpu_vm	*vm;
 	struct amdgpu_ring	*ring;
 	struct amdgpu_sync	sync;
+	struct amdgpu_sync	sched_sync;
 	struct amdgpu_ib	*ibs;
 	struct dma_fence	*fence; /* the hw fence */
 	uint32_t		preamble_status;