s390/pai_crypto: use PERF_ATTACH_TASK define for per task detection

Use define PERF_ATTACH_TASK bit in event->attach_state to determine
system wide invocation or per task invocation in event initialization.
This bit is set in common code and before calling PMU device driver
specific event initialization.
It is set once and never changes. It is save to use and also in
sync with other PMU specific code.
No functional change.

Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>