virtio-net: fix recursived rtnl_lock() during probe()

virtio-net: fix recursived rtnl_lock() during probe()

The deadlock appears in a stack trace like:

  virtnet_probe()
    rtnl_lock()
    virtio_config_changed_work()
      netdev_notify_peers()
        rtnl_lock()

It happens if the VMM sends a VIRTIO_NET_S_ANNOUNCE request while the
virtio-net driver is still probing.

The config_work in probe() will get scheduled until virtnet_open() enables
the config change notification via virtio_config_driver_enable().

Fixes: df28de7b0050 ("virtio-net: synchronize operstate with admin state on up/down")
Signed-off-by: Zigit Zo <zuozhijie@bytedance.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20250716115717.1472430-1-zuozhijie@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>