s390/cpumf: beautify if-then-else indentation

Beautify if-then-else indentation to match coding guideline.
Also use shorter pointer notation hwc instead of event->hw.

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