!10671 [MS][LITE]fix bug of tf model parser for identity const

From: @mengyuanli
Reviewed-by: @hangangqiang,@zhanghaibo5
Signed-off-by: @hangangqiang

mindspore/lite/tools/converter/legacy_optimizer/graph/switch_pass.cc

@@ -209,6 +209,7 @@ STATUS SingleSwitchPass::InsertMerge() {
       merge_node->inputIndex.push_back(old_merge_input[i]);
     } else {
       auto tensor = NewTensor(in_tensor);
+      tensor->nodeType = schema::NodeType_CNode;
       graph_->allTensors.push_back(std::move(tensor));
       merge_node->inputIndex.push_back(graph_->allTensors.size() - 1);
     }

mindspore/lite/tools/converter/parser/tf/tf_node_parser.cc

@@ -37,6 +37,14 @@ const NodeDef *TFNodeParser::GetConstInputNode(const std::map<string, const tens
     return nullptr;
   }
   auto node = tf_node_map.at(flatten_input_name);
+  // node is "Identity Const"
+  if (node->op() == "Identity") {
+    flatten_input_name = TensorFlowUtils::GetFlattenNodeName(node->input(0));
+    if (tf_node_map.find(flatten_input_name) == tf_node_map.end()) {
+      return nullptr;
+    }
+    node = tf_node_map.at(flatten_input_name);
+  }
   if (node->op() != "Const") {
     MS_LOG(ERROR) << "Attr node is not Const";
     return nullptr;