perf_counter: Fix perf-$cmd invokation

Fix:

  $ perf-top
  fatal: cannot handle -top internally
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090525124559.995591577@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/perf_counter/perf.c

@@ -357,7 +357,7 @@ int main(int argc, const char **argv)
 	 * die if that one cannot handle it.
 	 */
 	if (!prefixcmp(cmd, "perf-")) {
-		cmd += 4;
+		cmd += 5;
 		argv[0] = cmd;
 		handle_internal_command(argc, argv);
 		die("cannot handle %s internally", cmd);