Port elu to structured (#57619)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/57619
Test Plan: Imported from OSS
Reviewed By: VitalyFedyunin
Differential Revision: D28224707
Pulled By: ezyang
fbshipit-source-id: 9e1cad3f5536c65ada2d951366de134ebcb6bb3f
