[fix] type promotion atan2 (#43466)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/43360
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43466
Reviewed By: malfet
Differential Revision: D23834928
Pulled By: mruberry
fbshipit-source-id: 2e7e0b4fcf1a846efc171c275d65a6daffd3c631
