Fixes reduction launch config (#64304)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/48573
See also https://github.com/pytorch/pytorch/pull/64194
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64304
Reviewed By: janeyx99
Differential Revision: D30689600
Pulled By: ngimel
fbshipit-source-id: bf2103ca177fd3b6e27bc0324b81925234483a29
