iio: Use spi_sync_transfer()

Use the new spi_sync_transfer() helper function instead of open-coding it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/dac/ad5504.c

@@ -85,11 +85,7 @@ static int ad5504_spi_read(struct spi_device *spi, u8 addr)
 			.rx_buf		= &val,
 			.len		= 2,
 		};
-	struct spi_message	m;
-
-	spi_message_init(&m);
-	spi_message_add_tail(&t, &m);
-	ret = spi_sync(spi, &m);
+	ret = spi_sync_transfer(spi, &t, 1);
 
 	if (ret < 0)
 		return ret;