Some name and variable cleanup (#20861)
Summary:
As a part of https://github.com/pytorch/pytorch/pull/20580 I noticed that we had some unusual variable naming in `summary.py`. This cleans it up and also removes some variables that weren't being used.
I'll wait until we have an `add_custom_scalars` test to land this.
cc lanpa natalialunova
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20861
Differential Revision: D15503420
Pulled By: orionr
fbshipit-source-id: 86d105a346198a1ca543d1c5d297804402ab5a0c
