mkdumprd: make use of the new get_luks_crypt_dev helper
    
    Resolves: bz1951415
    Upstream: fedora
    Conflict: None
    
    commit 85c725813b49ae9495841b4b55736a26079dc75d
    Author: Kairui Song <kasong@redhat.com>
    Date:   Thu Apr 8 01:41:21 2021 +0800
    
        mkdumprd: make use of the new get_luks_crypt_dev helper
    
        Simplfy the code and also improve the performance. udevadm call is
        heavy.
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Acked-by: Pingfan Liu <piliu@redhat.com>
    
    Signed-off-by: Kairui Song <kasong@redhat.com>