tracing: fix check for return value of register_module_notifier

return zero should be correct, so fix it.

[ Impact: eliminate incorrect syslog message ]
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: rostedt@goodmis.org
LKML-Reference: <1242545498-7285-1-git-send-email-tom.leiming@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/trace/ftrace.c

@@ -2826,7 +2826,7 @@ void __init ftrace_init(void)
 				  __stop_mcount_loc);
 
 	ret = register_module_notifier(&ftrace_module_nb);
-	if (!ret)
+	if (ret)
 		pr_warning("Failed to register trace ftrace module notifier\n");
 
 	return;