Revert D22418716: [JIT] Add support for backend-lowered submodules
Test Plan: revert-hammer
Differential Revision:
D22418716 (https://github.com/pytorch/pytorch/commit/6777ea19fe5947b88c239b5d02c0f2441a21a4ce)
Original commit changeset: d2b2c6d5d2cf
fbshipit-source-id: 5ce177e13cab0be60020f8979f9b6c520cc8654e
