!13856 clear memory after run op in CPU

From: @simson_wu
Reviewed-by: 
Signed-off-by:

mindspore/ccsrc/backend/session/cpu_session.cc

@@ -220,6 +220,7 @@ void CPUSession::RunOpImpl(const GraphInfo &graph_info, OpRunInfo *op_run_info,
 
   std::vector<tensor::TensorPtr> output_tensors;
   SetOutputFlags(*outputs, &output_tensors);
+  runtime_.RunOpClearMemory(kernel_graph.get());
   MS_LOG(INFO) << "Run Op end";
 }