check the existence of /sys/bus/ccwgroup/devices before trying to find online network device
    
    Resolves: bz1977543
    Upstream: Fedora
    Conflict: None
    
    commit 03f9b91351fcd245e8d9327c38de296f818ad115
    Author: Coiby Xu <coxu@redhat.com>
    Date:   Mon Jun 28 18:37:10 2021 +0800
    
        check the existence of /sys/bus/ccwgroup/devices before trying to find online network device
    
        /sys/bus/ccwgroup/devices doesn't exist for non-s390x machines which leads to
        the warning "find: '/sys/bus/ccwgroup/devices': No such file or directory".
        This warning can be eliminated by checking the existence of
        "/sys/bus/ccwgroup/devices" beforehand.
    
        Fixes: commit 7d472515688fb330eee76dac1c39ae628398f757
               ("Iterate /sys/bus/ccwgroup/devices to tell if we should set up rd.znet")
    
        Reported-by: Ruowen Qin <ruqin@redhat.com>
        BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1974618
        Signed-off-by: Coiby Xu <coxu@redhat.com>
        Acked-by: Kairui Song <kasong@redhat.com>
    
    Signed-off-by: Coiby Xu <coxu@redhat.com>