Port gelu_backward to structured (#58665)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/58665
Test Plan: Imported from OSS
Reviewed By: mrshenli
Differential Revision: D28572527
Pulled By: ezyang
fbshipit-source-id: 0cb286f20c5f91453594a7dfe39ae4e4d24a13a1
