Revert replicate.py to disallow replicating multi-device modules (#19278)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19278
Based on discussion in https://github.com/pytorch/pytorch/pull/19278 and https://github.com/pytorch/pytorch/pull/18687, changes to replicate.py will be reverted to disallow replicating multi-device modules.
Reviewed By: pietern
Differential Revision: D14940018
fbshipit-source-id: 7504c0f4325c2639264c52dcbb499e61c9ad2c26
