[tests] use the correct `n_gpu` in...

[tests] use the correct `n_gpu` in `TrainerIntegrationTest::test_train_and_eval_dataloaders` for XPU (#29307)

* fix n_gpu

* fix style

tests/trainer/test_trainer.py

@@ -1029,7 +1029,10 @@ class TrainerIntegrationTest(TestCasePlus, TrainerIntegrationCommon):
         self.assertFalse(is_any_loss_nan_or_inf(log_history_filter))
 
     def test_train_and_eval_dataloaders(self):
-        n_gpu = max(1, backend_device_count(torch_device))
+        if torch_device == "cuda":
+            n_gpu = max(1, backend_device_count(torch_device))
+        else:
+            n_gpu = 1
         trainer = get_regression_trainer(learning_rate=0.1, per_device_train_batch_size=16)
         self.assertEqual(trainer.get_train_dataloader().total_batch_size, 16 * n_gpu)
         trainer = get_regression_trainer(learning_rate=0.1, per_device_eval_batch_size=16)