iio: adc: add missing of_node references to iio_dev

Adding missing indio_dev->dev.of_node references to allow iio consumers
to access the device channels.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/ad7923.c b/drivers/iio/adc/ad7923.c
index 1337116..77a675e 100644
--- a/drivers/iio/adc/ad7923.c
+++ b/drivers/iio/adc/ad7923.c
@@ -288,6 +288,7 @@
 
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = info->channels;
 	indio_dev->num_channels = info->num_channels;