Bugfix: support unknown control op subgraph

tests/ut/ge/hybrid/ge_hybrid_unittest.cc

@@ -263,7 +263,7 @@ TEST_F(UtestGeHybrid, unfold_subgraphs_success) {
   ComputeGraphPtr sub_graph = std::make_shared<ComputeGraph>("sub_graph");
   OpDescPtr sub_graph_while_op_desc = CreateOpDesc("while", WHILE);
   NodePtr sub_graph_while_node = sub_graph->AddNode(sub_graph_while_op_desc);
-  sub_graph->SetGraphUnknownFlag(True);
+  sub_graph->SetGraphUnknownFlag(true);
 
   ComputeGraphPtr sub_sub_graph1 = std::make_shared<ComputeGraph>("while_cond");
   OpDescPtr sub_sub_graph_while_cond_data_op_desc = CreateOpDesc("cond_data", DATA);