Migrate masked_fill__cuda to ATen (#51404)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/49543
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51404
Reviewed By: mrshenli
Differential Revision: D26329833
Pulled By: ngimel
fbshipit-source-id: 510988888fad015239ab4766eb391a89b742130b
