Fix typing errors in torch.distributed.nn.* directory. (#47533)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47533
Test Plan: Imported from OSS
Reviewed By: walterddr
Differential Revision: D24952500
Pulled By: xuzhao9
fbshipit-source-id: 8e66784fd8f9f111b6329e0bb48d6cd61c690a4a
