Fix creating generator everytime (#1301)

Summary: Pull Request resolved: #1301

Reviewed By: AkshatSh

Differential Revision: D20820109

fbshipit-source-id: 980f5af3ea698af859510512c176d1eeea965b49

Author: arbabu123

pytext/models/seq_models/seq2seq_model.py

@@ -125,8 +125,6 @@ def __init__(
     ):
         BaseModel.__init__(self)
         self.model = model
-        self.encoder = self.model.encoder
-        self.decoder = self.model.decoder
         self.output_layer = output_layer
 
         # Sequence generation is expected to be used only for inference, and to