wifi: virt_wifi: don't transfer operstate before register

In the Linux kernel, the following vulnerability has been resolved: wifi: virt_wifi: don't transfer operstate before register virt_wifi_newlink() calls netif_stacked_transfer_operstate() before register_netdevice(). If the lower device is dormant, that queues the new netdev on lweventlist while it is still uninitialized. If registration fails after that, for example because of an invalid name such as "bad/name", free_netdev() immediately frees the object. A later linkwatch_fire_event() then use-after-frees the list entry. Move the transfer to after netdev_upper_dev_link(), as macvlan and ipvlan already do.

Where it's fixed