Refactor ForeachUnaryOp.cu (#51894)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/51894
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D26323605
Pulled By: izdeby
fbshipit-source-id: eb65269ab3e14160d7cb5e6e84e85ef4037d3b0d
