perf powerpc: Support CPU ID matching for Powerpc

Implement code that returns the generic CPU ID string for Powerpc.  This
will be used to identify the specific table of PMU events to
parse/compare user specified events against.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1473978296-20712-5-git-send-email-sukadev@linux.vnet.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/powerpc/util/header.c

@@ -32,3 +32,14 @@ get_cpuid(char *buffer, size_t sz)
 	}
 	return -1;
 }
+
+char *
+get_cpuid_str(void)
+{
+	char *bufp;
+
+	if (asprintf(&bufp, "%.8lx", mfspr(SPRN_PVR)) < 0)
+		bufp = NULL;
+
+	return bufp;
+}