Update backward formulas (Re #44444) (#46275)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46275
Re #44444
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D24285785
Pulled By: anjali411
fbshipit-source-id: c60ecd4fe4f144132085f2c91d3b950e92b2a491
