Use unified interface in Ascend kernel (#2945)

mmcv/ops/csrc/pytorch/npu/voxelization_npu.cpp

@@ -18,7 +18,7 @@ int hard_voxelize_forward_npu(const at::Tensor &points, at::Tensor &voxels,
                               const std::vector<float> coors_range,
                               const int max_points, const int max_voxels,
                               const int NDim = 3) {
-  at::Tensor voxel_num_tmp = OpPreparation::ApplyTensor(points, {1});
+  at::Tensor voxel_num_tmp = at::empty({1}, points.options());
   at::Tensor voxel_num = voxel_num_tmp.to(at::kInt);
 
   at::Tensor voxel_size_cpu = at::from_blob(