drm/amdgpu: use kernel fence for last_pt_update

Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Christian K?nig <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <jammy.zhou@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index fe81b46..aee5911 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -581,7 +581,7 @@
 			if (r)
 				return r;
 
-			f = &bo_va->last_pt_update->base;
+			f = bo_va->last_pt_update;
 			r = amdgpu_sync_fence(adev, &p->ibs[0].sync, f);
 			if (r)
 				return r;