Fix `test_number_of_steps_in_training_with_ipex`
# What does this PR do?

Fix `test_number_of_steps_in_training_with_ipex`.

## Details
This test uses `no_cuda=True`, which will change `n_gpu` to `0` (see `_setup_devices`), and `train_batch_size` will be `8` (with the default training args). However this line
https://github.com/huggingface/transformers/blob/93f48da2740ab69fd14e6bbb38d53c87b4809eda/tests/trainer/test_trainer.py#L590
is computed (earlier) with GPUs, and therefore the (total) batch size is `16` when 2 GPUs is available.

This cause the following error.

#### Currently test error
```bash
tests/trainer/test_trainer.py::TrainerIntegrationTest::test_number_of_steps_in_training_with_ipex
(line 652)  AssertionError: 24 != 12.0
```
_The documentation is not available anymore as the PR was closed or merged._