hwmon: (emc2103) Fix use of an uninitilized variable in error case

Fix:

emc2103.c: In function set_pwm_enable:
emc2103.c:463:12: warning: conf_reg may be used uninitialized in this function

by checking the return value from read_u8_from_i2c(). This fixes a real problem,
as conf_reg is really uninitialized if read_u8_from_i2c returns an error.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/emc2103.c

@@ -451,11 +451,15 @@ static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *da,
 		data->fan_rpm_control = true;
 		break;
 	default:
-		mutex_unlock(&data->update_lock);
-		return -EINVAL;
+		count = -EINVAL;
+		goto err;
 	}
 
-	read_u8_from_i2c(client, REG_FAN_CONF1, &conf_reg);
+	result = read_u8_from_i2c(client, REG_FAN_CONF1, &conf_reg);
+	if (result) {
+		count = result;
+		goto err;
+	}
 
 	if (data->fan_rpm_control)
 		conf_reg |= 0x80;
@@ -463,7 +467,7 @@ static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *da,
 		conf_reg &= ~0x80;
 
 	i2c_smbus_write_byte_data(client, REG_FAN_CONF1, conf_reg);
-
+err:
 	mutex_unlock(&data->update_lock);
 	return count;
 }