Simplify complex case for `div_cpu` (#39996)
Summary:
Simplify complex case for `div_cpu`
cc: zasdfgbnm
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39996
Differential Revision: D22169715
Pulled By: anjali411
fbshipit-source-id: e1822ee5c575cb8786b395c1bc7550890b38a60d
