AttributeError: module 'open3d.cpu.pybind.geometry' has no attribute 'estimate_normals'

### 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).

### Steps to reproduce the issue

The problematic statement is open3d.geometry.estimate_normals(pcd,search_param=open3d.geometry.KDTreeSearchParamHybrid(radius=0.1, max_nn=30))

### Error message

```shell
D:\Anaconda3\python.exe "F:\wangluo\Projection correction\PFH.py"
Traceback (most recent call last):
File "F:\wangluo\Projection correction\PFH.py", line 7, in
open3d.geometry.estimate_normals(pcd, search_param=open3d.geometry.KDTreeSearchParamHybrid(radius=0.1, max_nn=30))
AttributeError: module 'open3d.cpu.pybind.geometry' has no attribute 'estimate_normals'

Process finished with exit code 1
```

### Open3D, Python and System information

```markdown
- Operating system:Windows 11 64-bit
- Python version: Python 3.7
- Open3D version: 0.15.1
- System architecture: x86
- Is this a remote workstation?: no
- How did you install Open3D?: pip
- Compiler version (if built from source): gcc 7.5 / clang 7.0
```

### Additional information