perf powerpc: Include util/util.h and remove stringify macros

The stringify macros are defined in tools/perf/util/util.h and don't
need to be redfined specfiically for powerpc.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Link: http://lkml.kernel.org/r/20140724074718.GB18829@us.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>