iio: adc: ti-ads1119: 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>
Reviewed-by: João Paulo Gonçalves <jpaulo.silvagoncalves@gmail.com>
Link: https://patch.msgid.link/20240726-dev-iio-masklength-private3-v1-13-82913fc0fb87@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ti-ads1119.c

@@ -435,7 +435,7 @@ static int ads1119_triggered_buffer_preenable(struct iio_dev *indio_dev)
 	int ret;
 
 	index = find_first_bit(indio_dev->active_scan_mask,
-			       indio_dev->masklength);
+			       iio_get_masklength(indio_dev));
 
 	ret = ads1119_set_conv_mode(st, true);
 	if (ret)
@@ -508,7 +508,7 @@ static irqreturn_t ads1119_trigger_handler(int irq, void *private)
 
 	if (!iio_trigger_using_own(indio_dev)) {
 		index = find_first_bit(indio_dev->active_scan_mask,
-				       indio_dev->masklength);
+				       iio_get_masklength(indio_dev));
 
 		ret = ads1119_poll_data_ready(st, &indio_dev->channels[index]);
 		if (ret) {