Remove duplicate header include. (#33656)
Summary:
The same header `<torch/nn/functional/conv.h>` is included twice.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33656
Differential Revision: D20056913
Pulled By: yf225
fbshipit-source-id: b1563035c9821731b99c26eec130ff0b9cc627a7
