Unify device() return type in Stream, Event, and Tensor (#16150)
Summary:
Addresses one future work item in #15937
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16150
Differential Revision: D13732299
Pulled By: mrshenli
fbshipit-source-id: 4d0b35df573a3bf92dea6e2e7eb42fe8bac77b18
