fix unique for discontiguous inputs (#59003)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/58959
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59003
Reviewed By: mruberry
Differential Revision: D28714534
Pulled By: ngimel
fbshipit-source-id: d9bf82f54be5b5919e27281e49fad74e00d8b766
