Make intdiv_256 a more generic binary operator template (#35422)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35422
This would make `intdiv_256` a much more generic template that can easily accommodate other types of binary operators in the future. The operator becomes "out-of-place" because this would make it easier to substitute with other operators, and compilers should have no problem optimizing this.
Test Plan: Imported from OSS
Differential Revision: D20826861
Pulled By: ngimel
fbshipit-source-id: a6d0706cc1a585063426e988d9982bad402a9b36
