iio: dac: ad5592r: 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: 56ca9db862bf ("iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs")
Signed-off-by: Jonathan Cameron <[e-mail]>
Cc: Paul Cercueil <[e-mail]>
Acked-by: Nuno Sá <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/iio/dac/ad5592r-base.h

···
 #include <linux/mutex.h>
 #include <linux/gpio/driver.h>
 
+#include <linux/iio/iio.h>
+
 struct device;
 struct ad5592r_state;
 
···
 	u8 gpio_in;
 	u8 gpio_val;
 
-	__be16 spi_msg ____cacheline_aligned;
+	__be16 spi_msg __aligned(IIO_DMA_MINALIGN);
 	__be16 spi_msg_nop;
 };