hwmon: (powr1220) Rely on subsystem locking

Attribute access is now serialized in the hardware monitoring core,
so locking in the driver code is no longer necessary. Drop it.

Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/powr1220.c

···
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
-#include <linux/mutex.h>
 #include <linux/delay.h>
 
 #define ADC_STEP_MV			2
···
 
 struct powr1220_data {
 	struct i2c_client *client;
-	struct mutex update_lock;
 	u8 max_channels;
 	bool adc_valid[MAX_POWR1220_ADC_VALUES];
 	 /* the next value is in jiffies */
···
 	int result;
 	int adc_range = 0;
 
-	mutex_lock(&data->update_lock);
-
 	if (time_after(jiffies, data->adc_last_updated[ch_num] + HZ) ||
 	    !data->adc_valid[ch_num]) {
 		/*
···
 		/* set the attenuator and mux */
 		result = i2c_smbus_write_byte_data(data->client, ADC_MUX,
 						   adc_range | ch_num);
-		if (result)
-			goto exit;
+		if (result < 0)
+			return result;
 
 		/*
 		 * wait at least Tconvert time (200 us) for the
···
 		/* get the ADC reading */
 		result = i2c_smbus_read_byte_data(data->client, ADC_VALUE_LOW);
 		if (result < 0)
-			goto exit;
+			return result;
 
 		reading = result >> 4;
 
 		/* get the upper half of the reading */
 		result = i2c_smbus_read_byte_data(data->client, ADC_VALUE_HIGH);
 		if (result < 0)
-			goto exit;
+			return result;
 
 		reading |= result << 4;
 
···
 	} else {
 		result = data->adc_values[ch_num];
 	}
-
-exit:
-	mutex_unlock(&data->update_lock);
-
 	return result;
 }
 
···
 		break;
 	}
 
-	mutex_init(&data->update_lock);
 	data->client = client;
 
 	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,