[TensorExpr] Remove unused functions in kernel.cpp (#43966)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/43966
Test Plan: build.
Reviewed By: ZolotukhinM
Differential Revision: D23456660
Pulled By: asuhan
fbshipit-source-id: c13411b61cf62dd5d038e7246f79a8682822b472
