Fix #7452 save new IPv6 gateway
This is also needed, just like for IPv4 in commit https://github.com/pfsense/pfsense/commit/f3278171b199062279225631903685e608285d3a
Fix #7452 save new IPv6 gateway
This is also needed, just like for IPv4 in commit https://github.com/pfsense/pfsense/commit/f3278171b199062279225631903685e608285d3a