oprofile, s390: Add support for IBM zEnterprise EC12

This patch adds support for the latest release of the
IBM mainframe series - the IBM zEnterprise EC12 (zEC12).

The CPU measurement facility didn't change.  So only the new CPU type
has to be tolerated.

Signed-off-by: Andreas Krebbel <krebbel@linux.vnet.ibm.com>
Signed-off-by: Robert Richter <rric@kernel.org>