Statement seems to have no effect
### System Info

transformers from `v4.3.3` to `v4.25.1`.

### Who can help?

@sgugger

### Information

- [ ] The official example scripts
- [ ] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

Just stare at [this line][1] (method is not actually called).
```python
class Trainer:
    def __init__(self, ...)
        ...

        # force device and distributed setup init explicitly
        args._setup_devices

        ...
```
This change was done in 2021-02-11 (almost two years ago).

[1]: https://github.com/huggingface/transformers/blob/4e730b387364c9f46b6b1b0c79fdaf0903c42257/src/transformers/trainer.py#L329

### Expected behavior

I do not know what to expect because of the issue. May be all distributed (at least parallel) training with PyTorch is broken. May be everything is fine. I am totally not sure. I'd like to see some regression tests or something that prove that there is not issue or something what was broken after this change.
It turns out that this is not a function but a property which do some complex initialization. :shrug:
