Aligning labels with output from o3d.t.geometry.PointCloud.create_from_rgbd_image()

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

Hello,

I'm creating a tensor pointcloud using `o3d.t.geometry.PointCloud.create_from_rgbd_image()` on GPU, using a depth map of shape `(H,W)`.

Now, I also have a `segmentation_map` image of shape `(H,W)` containing labels for each point. On non-tensorbased open3d pointclouds, I can easily align my labels with my pointcloud, because `pointcloud.points` is aligned with `segmentation_map.flatten()`. However, the alignment isn't correct on tensor based pointcloud / GPU...

Any idea?

Thanks!