Revert "s390/kdump: Clear subchannel ID to signal non-CCW/SCSI IPL"

Revert "s390/kdump: Clear subchannel ID to signal non-CCW/SCSI IPL"

This reverts commit 631278497d8b34166861ae54129dcee50decce45.

There are use cases where an intermediate boot kernel (1) uses kexec
to boot the final production kernel (2). For this scenario we should
provide the original boot information to the production kernel (2).
Therefore clearing the boot information during kexec() should not
be done.

Cc: stable@vger.kernel.org # v3.17+
Reported-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>