CUDA BFloat16 gelu, hardswish, hardsigmoid (#44997)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44997
Reviewed By: izdeby
Differential Revision: D24547748
Pulled By: ngimel
fbshipit-source-id: 34639dfe6ca41c3f59fd2af861e5e3b1bb86757a
