dscpPolicy: use bpf_net_helpers.h am: 85c9c994ca

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3226109

Change-Id: Id50bee42c81567e8cf074e735a2b01ee986e2da7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>