Add a hook to wait for kdump target in initqueue
    
    The dracut initqueue may quit immediately and won't trigger any hook if
    there is no "finished" hook still pending (finished hook will be deleted
    once it return 0).
    
    This issue start to appear with latest dracut, latest dracut use
    network-manager to configure the network,
    network-manager module only install "settled" hook, and we didn't
    install any other hook. So NFS/SSH dump will fail. iSCSI dump works
    because dracut iscsi module will install a "finished" hook to detect if
    the iscsi target is up.
    
    So for NFS/SSH we keep initqueue running until the host successfully get
    a valid IP address, which means the network is ready.
    
    Signed-off-by: Kairui Song <kasong@redhat.com>
    Acked-by: Pingfan Liu <piliu@redhat.com>