call DoRunWitType on Layernorm (#39409)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39409
enable running Layernorm fake op
Test Plan: ran the test, results are incorrect
Reviewed By: amylittleyang
Differential Revision: D21845269
fbshipit-source-id: 114e26e4fea80c0a8ab27501503c3ec0dc2fafb5
