Revert D32498569: allow external backend codegen to toggle whether to generate out= and inplace kernels
Test Plan: revert-hammer
Differential Revision:
D32498569 (https://github.com/pytorch/pytorch/commit/aa0cf68c1767bea886a3caaea49ac197e0ff64cf)
Original commit changeset: ebd932d042b9
Original Phabricator Diff: D32498569 (https://github.com/pytorch/pytorch/commit/aa0cf68c1767bea886a3caaea49ac197e0ff64cf)
fbshipit-source-id: 21a393fa339510d926512a7983d33ece327b743d
