hwmon: (nzxt-smart2) Use devm_mutex_init()

Use devm_mutex_init() instead of hand-writing it.

This saves some LoC, improves readability and saves some space in the
generated .o file.

Before:
======
text data bss dec hex filename
25878 11329 128 37335 91d7 drivers/hwmon/nzxt-smart2.o

After:
=====
text data bss dec hex filename
25551 11257 128 36936 9048 drivers/hwmon/nzxt-smart2.o

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/f51fac0871[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/nzxt-smart2.c

···
 	return init_device(drvdata, drvdata->update_interval);
 }
 
-static void mutex_fini(void *lock)
-{
-	mutex_destroy(lock);
-}
-
 static int nzxt_smart2_hid_probe(struct hid_device *hdev,
 				 const struct hid_device_id *id)
 {
···
 
 	init_waitqueue_head(&drvdata->wq);
 
-	mutex_init(&drvdata->mutex);
-	ret = devm_add_action_or_reset(&hdev->dev, mutex_fini, &drvdata->mutex);
+	ret = devm_mutex_init(&hdev->dev, &drvdata->mutex);
 	if (ret)
 		return ret;