Remove namespace F = torch::nn::functional from torch/nn/modules/batchhnorm.h (#30684)
Summary:
This PR removes `namespace F = torch::nn::functional` from `torch/nn/modules/batchhnorm.h`, so that people don't have to define `torch::nn::functional` as `F` if they don't want to.
Fixes https://github.com/pytorch/pytorch/issues/30682.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30684
Differential Revision: D18795717
Pulled By: yf225
fbshipit-source-id: c9feffbeb632cc6b4ce3e6c22c0a78533bab69ad
