[NNC] Handle non literal constant bounds in Unroll. (#53029)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/53000
Also added test to confirm this case works in FlattenLoop as well.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53029
Reviewed By: bertmaher
Differential Revision: D26742705
Pulled By: navahgar
fbshipit-source-id: d87a0f9698411026b5b6e55eee7c2b9fb123d06b
