Fix bp of roi perspective transform op. (#17216)

paddle/fluid/operators/detection/roi_perspective_transform_op.cu

@@ -466,6 +466,10 @@ class CUDAROIPerspectiveTransformGradOpKernel : public framework::OpKernel<T> {
     auto* in_grad = ctx.Output<framework::Tensor>(framework::GradVarName("X"));
 
     T* in_grad_data = in_grad->mutable_data<T>(ctx.GetPlace());
+
+    math::SetConstant<platform::CUDADeviceContext, T> set_zero;
+    set_zero(ctx.cuda_device_context(), in_grad, static_cast<T>(0));
+
     const T* out_grad_data = out_grad->data<T>();
     const int* out2in_idx_data = out2in_idx->data<int>();
     const T* out2in_w_data = out2in_w->data<T>();