fixed word level extract features for roberta-xlmr
fixed word level extract features for roberta-xlmr

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/933

Differential Revision: D18783780

fbshipit-source-id: fa0a27fab886a5fa5be8d5f49151d1d9dd9775f1

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq