Make OpenWRT IP address changable dynamically based on base_instance_num am: 6df3b6e14d am: 8366435d89

Original change: https://android-review.googlesource.com/c/platform/external/openwrt-prebuilts/+/2369050

Change-Id: I0f852e97d1f1be4f0236fc5bd81fba467e8d0d65
Signed-off-by: Automerger Merge Worker <[email protected]>