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>
diff --git a/drivers/iio/dac/ad5764.c b/drivers/iio/dac/ad5764.c
index 7f9045e..5b7acd3 100644
--- a/drivers/iio/dac/ad5764.c
+++ b/drivers/iio/dac/ad5764.c
@@ -135,7 +135,6 @@
 	unsigned int *val)
 {
 	struct ad5764_state *st = iio_priv(indio_dev);
-	struct spi_message m;
 	int ret;
 	struct spi_transfer t[] = {
 		{
@@ -148,15 +147,11 @@
 		},
 	};
 
-	spi_message_init(&m);
-	spi_message_add_tail(&t[0], &m);
-	spi_message_add_tail(&t[1], &m);
-
 	mutex_lock(&indio_dev->mlock);
 
 	st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16));
 
-	ret = spi_sync(st->spi, &m);
+	ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
 	if (ret >= 0)
 		*val = be32_to_cpu(st->data[1].d32) & 0xffff;