snake_case FX IR names (#50876)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50876
Test Plan: Imported from OSS
Reviewed By: nikithamalgifb
Differential Revision: D26002640
Pulled By: ansley
fbshipit-source-id: 4de8a63ef227ae3d46fab231f739c8472289ca4d
