team: restore port configuration after teamd respawn

If teamd crashes, we restore it. That's very nice, but if it really crashed then it left ports attached and the slave connections are not going to fail and the port configuration (e.g. priority or link watcher) in teamd's memory will be gone.

This will restore the port configuration when the teamd connection is re-established. This probably also fixes a race where a slave connection would be enslaved (only possible externally and manually?) while we didn't establish a connection to teamd yet. We'll just send the port configuration in once're connected.