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: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NJiri 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: NArnaldo 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;
+}