95znet: Add a rd.znet_ifname= option
    
    qeth device may have a different IP for each boot, so the rd.ifname=
    option will no longer work. So for znet device, introduce a
    rd.znet_ifname= options, to subchannel id instead of MAC address as the
    identifier and rename the interface.
    
    Signed-off-by: Kairui Song <kasong@redhat.com>
    (cherry picked from commit 872eb69936bd849eec6d1974dd6569f23a7ad3db)
    
    Resolves: #1811977
    
    patch_name: 0081.patch
    present_in_specfile: true
    location_in_specfile: 81
    squash_commits: true