mkdumprd: display the absolute path of dump location in the check_user_configured_target()
    
    upstream: fedora
    resolves: bz2003832
    conflict: none
    
    commit 2d9504c4a4dc5e2c659fbd8810b1fed681e5b4ba
    Author: Lianbo Jiang <lijiang@redhat.com>
    Date:   Tue Jun 1 18:33:44 2021 +0800
    
        mkdumprd: display the absolute path of dump location in the check_user_configured_target()
    
        When kdump service fails, the current errors do not display the
        absolute path of dump location(marked it as "^"), for example:
    
        kdump: kexec: unloaded kdump kernel
        kdump: Stopping kdump: [OK]
        kdump: Detected change(s) in the following file(s):  /etc/kdump.conf
        kdump: Rebuilding /boot/initramfs-4.18.0-304.el8.x86_64kdump.img
        kdump: Dump path "/var1/crash" does not exist in dump target "UUID=c202ef45-3ac3-4adb-85e7-307a916757f0"
                          ^^^^^^^^^^^
        kdump: mkdumprd: failed to make kdump initrd
        kdump: Starting kdump: [FAILED]
    
        Here, it should output the absolute path of dump location with this
        format: "<mount path>/<path>". To fix it, let's extend the relative
        pathname to the absolute pathname in check_user_configured_target().
    
        Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
        Acked-by: Kairui Song <kasong@redhat.com>
    
    Signed-off-by: Tao Liu <ltao@redhat.com>