!422 dataset: repeair GeneratorDataset to_device problem

Merge pull request !422 from ms_yan/Generator_distri

mindspore/dataset/engine/datasets.py

@@ -599,9 +599,9 @@ class Dataset:
 
         def get_distribution(output_dataset):
             dev_id = 0
-            if isinstance(output_dataset, (StorageDataset, GeneratorDataset, MindDataset)):
+            if isinstance(output_dataset, (StorageDataset, MindDataset)):
                 return output_dataset.distribution, dev_id
-            if isinstance(output_dataset, (Cifar10Dataset, Cifar100Dataset, ImageFolderDatasetV2,
+            if isinstance(output_dataset, (Cifar10Dataset, Cifar100Dataset, GeneratorDataset, ImageFolderDatasetV2,
                                            ManifestDataset, MnistDataset, VOCDataset, CelebADataset)):
                 sampler = output_dataset.sampler
                 if isinstance(sampler, samplers.DistributedSampler):