rtc: ds1374, fix lock imbalance

When i2c_smbus_read_byte_data fails in ds1374_work, we forgot to unlock
the held lock.  Fix that.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Scott Wood <scottwood@freescale.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-ds1374.c

@@ -283,7 +283,7 @@ static void ds1374_work(struct work_struct *work)
 
 	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 	if (stat < 0)
-		return;
+		goto unlock;
 
 	if (stat & DS1374_REG_SR_AF) {
 		stat &= ~DS1374_REG_SR_AF;
@@ -302,7 +302,7 @@ static void ds1374_work(struct work_struct *work)
 out:
 	if (!ds1374->exiting)
 		enable_irq(client->irq);
-
+unlock:
 	mutex_unlock(&ds1374->mutex);
 }