staging:iio:pollfunc: Make explicit that private data is always pointer to a struct iio_dev.

This is always true, so lets make it explicit.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/iio/imu/adis16400_ring.c b/drivers/staging/iio/imu/adis16400_ring.c
index ef38477..56385d3 100644
--- a/drivers/staging/iio/imu/adis16400_ring.c
+++ b/drivers/staging/iio/imu/adis16400_ring.c
@@ -111,7 +111,7 @@
 static irqreturn_t adis16400_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
-	struct iio_dev *indio_dev = pf->private_data;
+	struct iio_dev *indio_dev = pf->indio_dev;
 	struct adis16400_state *st = iio_priv(indio_dev);
 	struct iio_ring_buffer *ring = indio_dev->ring;
 	int i = 0, j, ret = 0;