s390/cio: Externalize full CMG characteristics

s390/cio: Externalize full CMG characteristics

The current "measurement_chars" CHPID sysfs attribute exposes only a
limited, validity-filtered portion of data from the associated Channel-
Measurements Characteristics Block (CMCB). New machine models add data
that is relevant for userspace tooling to the "header"-portion of the
CMCB. This data that is not currently accessible to userspace.

To prevent having to add new sysfs attributes whenever a new bit of data
is added to the CMCB "header", add a new sysfs attribute named
"measurement_chars_full" that exposes the full, unfiltered CMCB.

Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>