iio: adc: ti-ads1015: make use of iio_get_masklength()

Use iio_get_masklength() to access '.masklength' so it can be annotated
as __private when there are no more direct users of it.
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240726-dev-iio-masklength-private3-v1-12-82913fc0fb87@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ti-ads1015.c

@@ -456,7 +456,7 @@ static irqreturn_t ads1015_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->lock);
 	chan = find_first_bit(indio_dev->active_scan_mask,
-			      indio_dev->masklength);
+			      iio_get_masklength(indio_dev));
 	ret = ads1015_get_adc_result(data, chan, &res);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);