[S390] reboot from and dump to SCSI under z/VM fails.

We used wrong length values for ipl and dump hardware structures.
Since z/VM checks the ipl parameters more accurately than LPAR,
the operations fail there.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>