Exposing linear layer to fuser (#50856)
Summary:
1. enabling linear in autodiff;
2. remove control flow in python for linear;
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50856
Reviewed By: pbelevich
Differential Revision: D26105797
Pulled By: eellison
fbshipit-source-id: 6f7cedb9f6e3e46daa24223d2a6080880498deb4
