kdumpctl: fix fragile loops over find output
    
    upstream: fedora
    resolves: bz2003832
    conflict: none
    
    commit dfb76467c9d9462e91e4dd8838f461fb7ab2538f
    Author: Kairui Song <kasong@redhat.com>
    Date:   Wed Aug 4 16:22:17 2021 +0800
    
        kdumpctl: fix fragile loops over find output
    
        For loops over find output are fragile, use a while read loop:
        https://github.com/koalaman/shellcheck/wiki/SC2044
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Acked-by: Philipp Rudo 
    
    Signed-off-by: Tao Liu <ltao@redhat.com>