net-test: fix nduseropt parsing when multiple are present am: 67260f7cd2

Original change: https://android-review.googlesource.com/c/kernel/tests/+/3326575

Change-Id: Ia98779ebdb3bbae6afdee086a490a2d91e1e2a7c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>