Fix LayerNorm Bug (#28196)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28196
Fix LayerNorm Bug
Test Plan: buck test mode/dev-nosan caffe2/test:nn -- "LayerNorm"
Reviewed By: okhonko, houseroad
Differential Revision: D17973451
fbshipit-source-id: 865e4f295b8d6c0438ec8872da0b43d3c5d3d3c6
