[S390] cio: CHSC SIOSL Support

A Linux interface for the CHSC command
store-I/O-operation-status-and-initiate-logging (SIOSL).
Model-dependent logging within the channel subsystem can be invoked
via a helper function or a writable subchannel device attribute.

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