Add chkconfig package to fedora-arm-base.ks
    
    Both the kickstart itself and imgcreate expect chkconfig to be
    available in the installed system, so we'd better make sure it
    is. Up till Fedora 30 Beta it was getting pulled in somehow;
    since Fedora-30-20190330.n.3 it seems it is not (probably not
    in Rawhide either). In any case, it's clearly correct to list it
    explicitly.
    
    See https://bugzilla.redhat.com/show_bug.cgi?id=1695637
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>