Remove unused /sys/kernel/debug/zcore/memmap device.
Since at least version 1.24.0 of s390-tools zfcpdump no longer
needs it and reads /proc/vmcore instead.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>