iio: adc: ti-ads8344: Fix alignment for DMA safety

____cacheline_aligned is an insufficient guarantee for non-coherent DMA
on platforms with 128 byte cachelines above L1.  Switch to the updated
IIO_DMA_MINALIGN definition.

Fixes: 8dd2d7c0 ("iio: adc: Add driver for the TI ADS8344 A/DC chips")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-38-jic23@kernel.org

drivers/iio/adc/ti-ads8344.c

@@ -28,7 +28,7 @@ struct ads8344 {
 	 */
 	struct mutex lock;
 
-	u8 tx_buf ____cacheline_aligned;
+	u8 tx_buf __aligned(IIO_DMA_MINALIGN);
 	u8 rx_buf[3];
 };