Enabled BFloat16 storage (#21523)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21523
ghimport-source-id: 698b3cbd6b21c09b9ff8bf8011980df8e35c33b0
Test Plan: Imported from OSS
Differential Revision: D15819368
Pulled By: izdeby
fbshipit-source-id: f6b3bba7b3ca8ee677bd80a231dbb3920c07d61c
