s390/cpum_cf: Add support for CPU-MF SVN 6

Add support for the CPU-Measurement Facility counter
second version number 6. This number is used to detect some
more counters in the crypto counter set and the extended
counter set.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>