[quant][graphmode][refactor] Remove unused code in quantization.cpp (#37974)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/37974
Differential Revision: D21468498
Pulled By: jerryzh168
fbshipit-source-id: 96f34db9f98474ec8e5d33e9b7c406b1637f5de8
