DscpPolicyValue: just use '!= null' on original src/dst46 argument am: 5e7247d922 am: 0a5550137c

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3255777

Change-Id: I8c38b94e0a3afb48cf392bc6fe93157cc4a67025
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>