Fixed bug where we would die if there was no kdump.conf

Previously we'd die in some comparison functions for kdump config values, but this would fail if there was no kdump config. Now handle this properly.

Signed-off-by: Jake Hunsaker <jhunsake@redhat.com>
Changed format and strip leading /dev/mapper

Signed-off-by: Jake Hunsaker <jhunsake@redhat.com>