Symbolic for ReLu6 (#58560) (#59538)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59538
Four mealv2 models can export in torch 1.8.1, but fails when torch master introduces relu6 a few months back.
Test Plan: Imported from OSS
Reviewed By: nikithamalgifb, ansley
Differential Revision: D29046607
Pulled By: SplitInfinity
fbshipit-source-id: d9cf7050e4ac0dad892441305ffebc19ba84e2be
Co-authored-by: David <jiafa@microsoft.com>
