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

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

Change-Id: Icf5fe1c023eb3840a83abafe01e3ba2557c017c4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>