hwmon: (it87) Ensure that pwm control cache is current before updating values

If sensor attributes were never read, the pwm control data has not been
initiialized, which can cause wrong driver behavior. Ensure that cached
data is current before acting on it.

Cc: stable@vger.kernel.org # 4.4+
Reported-by: Kevin Folz <kfolz@evertz.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/it87.c

@@ -1360,6 +1360,7 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 
 	mutex_lock(&data->update_lock);
+	it87_update_pwm_ctrl(data, nr);
 	if (has_newer_autopwm(data)) {
 		/*
 		 * If we are in automatic mode, the PWM duty cycle register
@@ -1472,6 +1473,7 @@ static ssize_t set_pwm_temp_map(struct device *dev,
 	}
 
 	mutex_lock(&data->update_lock);
+	it87_update_pwm_ctrl(data, nr);
 	data->pwm_temp_map[nr] = reg;
 	/*
 	 * If we are in automatic mode, write the temp mapping immediately;