s390/cpumf: Support for CPU Measurement Facility CSVN 7

Adds support for the CPU Measurement Counter Facility second version
number 7.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>