CVE-2026-31579 wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit

In the Linux kernel, the following vulnerability has been resolved: wireguard: device: use exitrtnl callback instead of manual rtnllock in preexit wgnetnspreexit manually acquires rtnllock inside the pernet .preexit callback. This causes a hung task when another thread holds rtnlmutex - the...