hardswish reland (#57652)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/57652
Test Plan: Imported from OSS
Reviewed By: Krovatkin
Differential Revision: D28226724
Pulled By: eellison
fbshipit-source-id: 585a91ffab7a855b5600e79130a37be25ef9b354
