hwmon: (lm90) Only disable alerts if not already disabled

It was observed that the alert handler may be called from the i2c core
even after alerts have already been disabled. Only disable alerts if
they have not already been disabled.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/lm90.c

@@ -2660,8 +2660,10 @@ static void lm90_alert(struct i2c_client *client, enum i2c_alert_protocol type,
 
 		if ((data->flags & LM90_HAVE_BROKEN_ALERT) &&
 		    (data->current_alarms & data->alert_alarms)) {
-			dev_dbg(&client->dev, "Disabling ALERT#\n");
-			lm90_update_confreg(data, data->config | 0x80);
+			if (!(data->config & 0x80)) {
+				dev_dbg(&client->dev, "Disabling ALERT#\n");
+				lm90_update_confreg(data, data->config | 0x80);
+			}
 			schedule_delayed_work(&data->alert_work,
 				max_t(int, HZ, msecs_to_jiffies(data->update_interval)));
 		}