remove default params from args so architecture works properly
remove default params from args so architecture works properly

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/798

Reviewed By: myleott

Differential Revision: D16619502

Pulled By: alexeib

fbshipit-source-id: af20c90c4522458850d8f42cab001259ef4293cc

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq