[S390] Add ioctl support for EMC Symmetrix Subsystem Control I/O
EMC Symmetrix Subsystem Control I/O through CKD dasd requires a
specific parameter list sent to the array via a Perform Subsystem
Function CCW. The Symmetrix response is retrieved from the array
via a Read Subsystem Data CCW.
Signed-off-by: Nigel Hislop <hislop_nigel@emc.com> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>