Revert "per channel quantization support (#24936)" (#25131)
Summary:
This reverts commit 9e9965035ce92c7f3eda36fa9b18f4bc0042001b.
Since it is breaking master
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25131
Differential Revision: D16997422
Pulled By: zrphercule
fbshipit-source-id: cc467600fad4940e0db7b2387a0a6c938fe50470
