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

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

Change-Id: I8a03745f3437a3156149fc4b139bc26f4993f469
Signed-off-by: Automerger Merge Worker <[email protected]>