Have DeviceType available in torch namespace (#38036)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38036
Resolves: https://github.com/pytorch/pytorch/issues/36946
Test Plan: Imported from OSS
Differential Revision: D21463610
Pulled By: anjali411
fbshipit-source-id: c4aabfac2cd1f05f8b66745aae0a17c2af4d9c9b
