conf: Forbid device alias change on device-update
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1585108
    
    When updating a live device users might pass different alias than
    the one the device has. Currently, this is silently ignored which
    goes against our behaviour for other parts of the device where we
    explicitly allow only certain changes and error out loudly on
    anything else.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
    Reviewed-by: John Ferlan <jferlan@redhat.com>