remove useless input 'Softmax@GRAD' from softmax_with_cross_entropy op (#17612)

paddle/fluid/operators/softmax_with_cross_entropy_op.cc

@@ -248,7 +248,6 @@ class SoftmaxGradMaker : public framework::SingleGradOpDescMaker {
     grad_op->SetType("softmax_with_cross_entropy_grad");
     grad_op->SetInput("Label", Input("Label"));
     grad_op->SetInput("Softmax", Output("Softmax"));
-    grad_op->SetInput(framework::GradVarName("Softmax"), OutputGrad("Softmax"));
     grad_op->SetInput(framework::GradVarName("Loss"), OutputGrad("Loss"));
     grad_op->SetOutput(framework::GradVarName("Logits"), InputGrad("Logits"));
     grad_op->SetAttrMap(Attrs());