s390: add variable command line size
    
    Resolves: bz2060824
    Upstream: git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
    Conflicts: None
    
    commit defb80a20bf1e4d778596ce2447e19d44f31ae5a
    Author: Sven Schnelle <svens@linux.ibm.com>
    Date:   Thu Dec 16 12:43:52 2021 +0100
    
        s390: add variable command line size
    
        Newer s390 kernels support a command line size longer than 896
        bytes. Such kernels contain a new member in the parameter area,
        which might be utilized by tools like kexec. Older kernels have
        the location initialized to zero, so we check whether there's a
        non-zero number present and use that. If there isn't, we fallback
        to the legacy command line size of 896 bytes.
    
        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>