add helper functions to get dump mode
    
    Resolves: bz1895258
    Upstream: Fedora
    Conflict: None
    
    commit 3d2079c31cd80741ea6d44eb7f13d7f08be74a94
    Author: Coiby Xu <coxu@redhat.com>
    Date:   Wed Dec 1 16:57:15 2021 +0800
    
        add helper functions to get dump mode
    
        Add a helper function to get dump mode. The dump mode would be
         - fadump if fadump=on or fadump=nocma
         - kdump if fadump=off or empty fadump
    
        Otherwise return 1.
    
        Also add another helper function to return a kernel's dump mode.
    
        Reviewed-by: Pingfan Liu <piliu@redhat.com>
        Reviewed-by: Philipp Rudo <prudo@redhat.com>
        Signed-off-by: Coiby Xu <coxu@redhat.com>
    
    Signed-off-by: Coiby Xu <coxu@redhat.com>