s390/pai_crypto: Enable per-task counting event

s390/pai_crypto: Enable per-task counting event

The PMU for PAI crypto counters enforces the following restriction:

     - No per-task context for PAI crypto counters events.

This restriction is removed. One or more per-task/system-wide counting
events can now be active at the same time while at most one system
wide sampling event is active.

Example for per-task context of a PAI crypto counter event:
   # perf stat -e pai_crypto/KM_AES_128/ -- true

Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>