ARC: Fix ArcNetHostImpl unit tests

This patch fixes ArcNetHostImpl unit test failure.

Bug: b/360209881
Test: unit tests
Change-Id: Ie0b8b9ae99a48ae28f4faacc8038fba929ee98da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5825751


Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Hugo Benichi <hugobenichi@google.com>
Commit-Queue: Chuwei He <chuweih@google.com>
Cr-Commit-Position: refs/heads/main@{#1349189}