[nnapi] remove unused field 'order_' in nnapi.h (#84067)
Summary: This fixes the build
Test Plan: `buck build //xplat/caffe2:nnapi_benchmarkAndroid`
Reviewed By: salilsdesai
Differential Revision: D38924916
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84067
Approved by: https://github.com/SS-JIA
