Wait for device activation / "online" hook if rd.neednet is set
    
    If we're expecting network devices to come up, we need to tell dracut
    to wait for devices to activate before proceeding to stage 2, otherwise
    we won't have ifcfg files, and the NM handover will fail, and anaconda
    considers it a fatal error if a network device isn't active when the
    kickstart says it should be.
    
    (It would be nice if anaconda could set up the network itself so we
    didn't have to handle this all in initramfs..)