iio: potentiometer: max5481: 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: df1fd2de118e ("iio: max5481: Add support for Maxim digital potentiometers")
Signed-off-by: Jonathan Cameron <[e-mail]>
Acked-by: Nuno Sá <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/iio/potentiometer/max5481.c

···
 struct max5481_data {
 	struct spi_device *spi;
 	const struct max5481_cfg *cfg;
-	u8 msg[3] ____cacheline_aligned;
+	u8 msg[3] __aligned(IIO_DMA_MINALIGN);
 };
 
 #define MAX5481_CHANNEL {					\