s390: add support for --reuse-cmdline
    
    Resolves: bz2060824
    Upstream: git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
    Conflicts: None
    
    commit 2e1ec106dc5aac951ba884ebe4cca036e9a2d45f
    Author: Sven Schnelle <svens@linux.ibm.com>
    Date:   Thu Dec 16 12:43:56 2021 +0100
    
        s390: add support for --reuse-cmdline
    
        --reuse-cmdline reads the command line of the currently
        running kernel from /proc/cmdline and uses that for the
        kernel that should be kexec'd.
    
        Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
        Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
        Signed-off-by: Simon Horman <horms@verge.net.au>
    
    Signed-off-by: Philipp Rudo <prudo@redhat.com>