remove useless --zipl when calling grubby to update kernel command line
    
    Related: bz2104534
    Upstream: Fedora
    Conflict: None
    
    commit 58eef4582a5ec060a51a699839868d5b86fa2b05
    Author: Coiby Xu <coxu@redhat.com>
    Date:   Tue Jul 12 16:07:37 2022 +0800
    
        remove useless --zipl when calling grubby to update kernel command line
    
        "grubby --zipl" only takes effect when setting default kernel. It's
        useless to add "--zipl" when updating kernel command line. Also rename
        _update_grub to _update_kernel_cmdline since s390x doesn't use GRUB.
    
        Reviewed-by: Philipp Rudo <prudo@redhat.com>
        Signed-off-by: Coiby Xu <coxu@redhat.com>
    
    Signed-off-by: Coiby Xu <coxu@redhat.com>