[nnc][fix] xnnpack ifdef (#69870)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/69870
Test Plan: Imported from OSS
Reviewed By: ZolotukhinM
Differential Revision: D33075061
Pulled By: IvanKobzarev
fbshipit-source-id: dd53ad8b7d0ff36a68f0864540d6f7dd2284f0e0
