Alembic procedural: fix wrong property used as base for attribute

lookups

We use the schema so that we can access top level attributes as well.
This is already done for polygon meshes and curves, so this only
modifies the behavior for subdivision objects.

intern/cycles/render/alembic.cpp

@@ -500,7 +500,7 @@ void AlembicObject::load_data_in_cache(CachedData &cached_data,
    */
   read_attributes(proc,
                   cached_data,
-                  schema.getArbGeomParams(),
+                  schema,
                   schema.getUVsParam(),
                   get_requested_attributes(),
                   progress);