s390/cpumf: Adjust number of leading zeroes for z15 attributes

In CPUMF attribute definitions for z15 all CPUMF attributes
have configuration values of the form 0x0[0-9a-f]{3} .
However 2 defines do not match this scheme, they have two leading
zeroes instead of one. Adjust this. No functional change.

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