fix bug in dist train on hs, test=release/1.2

paddle/fluid/operators/hierarchical_sigmoid_op.cc

@@ -150,13 +150,12 @@ class HierarchicalSigmoidGradOp : public framework::OperatorWithKernel {
                    "Output(W@Grad should not be null.");
     PADDLE_ENFORCE(ctx->HasOutput(framework::GradVarName("X")),
                    "Output(X@Grad should not be null.");
-    if (!ctx->Attrs().Get<bool>("is_sparse")) {
+
     if (ctx->HasOutput(framework::GradVarName("Bias"))) {
       ctx->SetOutputDim(framework::GradVarName("Bias"),
                         ctx->GetInputDim("Bias"));
     }
     ctx->SetOutputDim(framework::GradVarName("W"), ctx->GetInputDim("W"));
-    }
     ctx->SetOutputDim(framework::GradVarName("X"), ctx->GetInputDim("X"));
   }