!1285 Remove MindConverter redundant code for external developer's contribution

From: @liangtianshu
Reviewed-by: @ouwenchang,@yelihua
Signed-off-by: @yelihua

mindinsight/mindconverter/graph_based_converter/third_party_graph/onnx_utils.py

@@ -502,14 +502,7 @@ class OnnxDataLoader:
 
     def _parse_graph(self):
         """Parse ONNX Graph Info For usage in generator."""
-        graph_inputs = [inp.name for inp in self.graph.input]
         graph_outputs = [out.name for out in self.graph.output]
-        for output_node in self.output_nodes:
-            if output_node not in graph_outputs:
-                raise ValueError(f"Unexpected Node {output_node} detected which should not be a graph output.")
-        for graph_inp in graph_inputs:
-            if graph_inp not in self.input_nodes.keys():
-                raise ValueError(f"{graph_inp} is one of the graph inputs but user does not provide it.")
         self._global_context.onnx_graph_info['graph_inputs'] = self.input_nodes.keys()
         self._global_context.onnx_graph_info['graph_outputs'] = graph_outputs
 
@@ -521,7 +514,7 @@ class OnnxDataLoader:
             if output_node not in graph_outputs:
                 raise ModelLoadingError(f"Unexpected Node {output_node} detected which should not be a graph output.")
         for graph_inp in graph_inputs:
-            if graph_inp not in self.input_nodes.keys():
+            if graph_inp not in self.input_nodes:
                 raise ModelLoadingError(f"{graph_inp} is one of the graph inputs but user does not provide it.")
 
     def initialize(self):