hwmon: (max6650) Fix lock imbalance

Add omitted update_lock to one switch/case in set_div.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
index 86142a8..58f66be 100644
--- a/drivers/hwmon/max6650.c
+++ b/drivers/hwmon/max6650.c
@@ -418,6 +418,7 @@
 		data->count = 3;
 		break;
 	default:
+		mutex_unlock(&data->update_lock);
 		dev_err(&client->dev,
 			"illegal value for fan divider (%d)\n", div);
 		return -EINVAL;