Update FP16 to FP16:4dfe081cf6bcd15db339cf2680b9281b8451eeb3. (#40526)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/40526
Differential Revision: D22215600
Pulled By: AshkanAliabadi
fbshipit-source-id: 6ff0c17d17f118b64ae34c0007b705c7127f07ef
