conf: Move the privateData from virDomainChrDef to virDomainChrSourceDef
    
    Commit id '5f2a132786' should have placed the data in the host source
    def structure since that's also used by smartcard, redirdev, and rng in
    order to provide a backend tcp channel.  The data in the private structure
    will be necessary in order to provide the secret properly.
    
    This also renames the previous names from "Chardev" to "ChrSource" for
    the private data structures and API's