Moving torch.norm to ATen using TensorIterator (#15414)
Summary:
Adding supports for torch.nomr:
i. multi dimensions for dim
ii. dtype that specifies math/output tensor type
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15414
Differential Revision: D13702022
Pulled By: ezyang
fbshipit-source-id: da2676f2b6aff988889b1539d0de8ecd4946823a
