fix addn in pynative mode

mindspore/ccsrc/pre_activate/ascend/ascend_backend_optimization.cc

@@ -240,6 +240,7 @@ void RunOpAscendBackendIRFusionOptimization(const std::shared_ptr<session::Kerne
   auto ir_fusion_pm = std::make_shared<PassManager>("ir_fusion_pm");
   ir_fusion_pm->AddPass(std::make_shared<BnSplit>());
   ir_fusion_pm->AddPass(std::make_shared<TopKSplit>());
+  ir_fusion_pm->AddPass(std::make_shared<AddnFission>());
 
   optimizer->AddPassManager(ir_fusion_pm);
   (void)optimizer->Optimize(kernel_graph);