[RFC] Remove per-op-registration related code in caffe2/tools/codegen/gen.py (#45134)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45134
Per-Op-Registration was a mechanism used for mobile selective build v0. Since then, a new dispathing mechanism has been built for PyTorch, and this code path isn't used any more. Remove it to simplify understanding/updating the code-generator's code-flow.
ghstack-source-id: 112723942
Test Plan: `buck build` and sandcastle.
Reviewed By: ezyang
Differential Revision: D23806632
fbshipit-source-id: d93cd324650c541d9bfc8eeff2ddb2833b988ecc
