drivers/macintosh/adb: Do not claim that the semaphore is a mutex

The usage of this "mutex" is non obvious and used as completion in
some places. Make it a semaphore.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/macintosh/adb.c

@@ -83,7 +83,7 @@ static struct adb_driver *adb_controller;
 BLOCKING_NOTIFIER_HEAD(adb_client_list);
 static int adb_got_sleep;
 static int adb_inited;
-static DECLARE_MUTEX(adb_probe_mutex);
+static DEFINE_SEMAPHORE(adb_probe_mutex);
 static int sleepy_trackpad;
 static int autopoll_devs;
 int __adb_probe_sync;