fix the bug of export model

deepspeech/models/ds2/deepspeech2.py

@@ -219,10 +219,10 @@ class DeepSpeech2Model(nn.Layer):
             The model built from pretrained result.
         """
         model = cls(
-            #feat_size=dataloader.collate_fn.feature_size,
-            feat_size=dataloader.dataset.feature_size,
-            #dict_size=dataloader.collate_fn.vocab_size,
-            dict_size=dataloader.dataset.vocab_size,
+            feat_size=dataloader.collate_fn.feature_size,
+            #feat_size=dataloader.dataset.feature_size,
+            dict_size=dataloader.collate_fn.vocab_size,
+            #dict_size=dataloader.dataset.vocab_size,
             num_conv_layers=config.model.num_conv_layers,
             num_rnn_layers=config.model.num_rnn_layers,
             rnn_size=config.model.rnn_layer_size,