drm/ttm: add BO priorities for the LRUs

This way the driver can specify a priority for a BO which has the effect that
a BO is only evicted when all other BOs with a lower priority are evicted
first.

Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Roger.He <Hongbo.He@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 652e45b..c356df4 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -215,6 +215,8 @@ struct ttm_buffer_object {
 
 	struct drm_vma_offset_node vma_node;
 
+	unsigned priority;
+
 	/**
 	 * Special members that are protected by the reserve lock
 	 * and the bo::lock when written to. Can be read with