iio: adc: twl4030-madc: Fix misnamed struct attribute

Fixes the following W=1 kernel build warning(s):

 drivers/iio/adc/twl4030-madc.c:170: warning: Function parameter or member 'usb3v1' not described in 'twl4030_madc_data'

Also drop a duplicate description of the lock.

Cc: J Keerthy <j-keerthy@ti.com>
Cc: Mikko Ylinen <mikko.k.ylinen@nokia.com>
Cc: Amit Kucheria <amit.kucheria@canonical.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/twl4030-madc.c

@@ -153,7 +153,7 @@ enum sample_type {
  * struct twl4030_madc_data - a container for madc info
  * @dev:		Pointer to device structure for madc
  * @lock:		Mutex protecting this data structure
- * @regulator:		Pointer to bias regulator for madc
+ * @usb3v1:		Pointer to bias regulator for madc
  * @requests:		Array of request struct corresponding to SW1, SW2 and RT
  * @use_second_irq:	IRQ selection (main or co-processor)
  * @imr:		Interrupt mask register of MADC
@@ -161,7 +161,7 @@ enum sample_type {
  */
 struct twl4030_madc_data {
 	struct device *dev;
-	struct mutex lock;	/* mutex protecting this data structure */
+	struct mutex lock;
 	struct regulator *usb3v1;
 	struct twl4030_madc_request requests[TWL4030_MADC_NUM_METHODS];
 	bool use_second_irq;