Remove qconfig_dict from API (#23465)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23465
We decided not to allow user to use qconfig_dict to do quantization
since that API is not robust.
Differential Revision: D16611504
fbshipit-source-id: b0d1d311b32c990a165c480f50e9ce3d68b785b5
