V4L/DVB (13721): [Mantis] Bug! Before bailing out, Unlock

Thanks to hotwings <user.vdr@gmail.com> for pointing out the bug
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/mantis/mantis_i2c.c

@@ -133,11 +133,15 @@ static int mantis_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, in
 			ret = mantis_i2c_write(mantis, &msgs[i]);
 
 		if (ret < 0)
-			return ret;
+			goto bail_out;
 	}
 	mutex_unlock(&mantis->i2c_lock);
 
 	return num;
+
+bail_out:
+	mutex_unlock(&mantis->i2c_lock);
+	return ret;
 }
 
 static u32 mantis_i2c_func(struct i2c_adapter *adapter)