update getNvpPnnxModel func comments

tools/pnnx/src/parse/pnnx_graph_parse.cpp

@@ -65,9 +65,9 @@ bool PnnxGraph::getNvpPnnxModel(const std::string& pt_path, const std::string& s
     std::strcpy( argv[argc - 2], end_nodes_info.c_str());
 
     //insert extract_model_name
-    std::string custom_op_py_info = "extract_model_name=" + custom_op_py;
-    argv[argc - 1] = new char[custom_op_py_info.size() + 1];
-    std::strcpy(argv[argc - 2], custom_op_py_info.c_str());
+    std::string extract_model_name_info = "extract_model_name=" + extract_model_name;
+    argv[argc - 1] = new char[extract_model_name_info.size() + 1];
+    std::strcpy(argv[argc - 1], extract_model_name_info.c_str());
 
     int result = main(argc, argv);
 

tools/pnnx/src/parse/pnnx_graph_parse.h

@@ -15,21 +15,24 @@ class PnnxGraph
      * @brief Get the Nvp Pnnx Model object
      *
      * @param pt_path torchscript path
+     * @param save_dir the dir of save pnnx 
      * @param input_shape input shape of tensor
      * @param custom_op_path the path of define custom op
      * @param custom_op_py the py path of define custom op
      * @param start_nodes the list of start nodes
      * @param end_nodes the list of end nodes
+     * @param extract_model_name the name of which to extract
      * @return true
      * @return false
      */
     bool getNvpPnnxModel(const std::string& pt_path, \
-     const std::string& save_dir, \
+    const std::string& save_dir, \
     const std::string& input_shape, \
     const std::string& custom_op_path, \
-    const std::string& custom_op_py,
-    const std::string& start_nodes = "",
-    const std::string& end_nodes = "");
+    const std::string& custom_op_py,\
+    const std::string& start_nodes = "",\
+    const std::string& end_nodes = "",\
+    const std::string& extract_model_name = "model");