Removed dead code from THTensorMath.h (#17769)
Summary:
This PR removes dead code from THTensorMath.h
I found these unused methods while working on a PR where i plan to move **fill** and **zero** methods from TH/THC to Aten.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17769
Differential Revision: D14372732
Pulled By: izdeby
fbshipit-source-id: 94fd3b52c691ebc89d2bdc8905452e7498038bf5
