perf vendor events powerpc: Update POWER9 events

Update and cleanup POWER9 PMU events.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Anton Blanchard <anton@au1.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: http://lkml.kernel.org/r/20170802174617.GA32545@us.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>