GSD-2022-1006625 ipv6: ensure sane device mtu in tunnels

ipv6: ensure sane device mtu in tunnels This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0.7 by commit ccd94bd4939690e24d13e23814bce7ed853a09f...