Fix a typo in Parallel.h (#16419)
Summary:
Fix a typo in Parallel.h.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16419
Differential Revision: D13833705
Pulled By: soumith
fbshipit-source-id: 824ebe753e028fc8e2b5d7a51fdba98a365fd29a
