iio: temp: max31865: 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: e112dc4e ("iio: temperature: Add MAX31865 RTD Support")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Navin Sankar Velliangiri <navin@linumiz.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-92-jic23@kernel.org

drivers/iio/temperature/max31865.c

@@ -55,7 +55,7 @@ struct max31865_data {
 	struct mutex lock;
 	bool filter_50hz;
 	bool three_wire;
-	u8 buf[2] ____cacheline_aligned;
+	u8 buf[2] __aligned(IIO_DMA_MINALIGN);
 };
 
 static int max31865_read(struct max31865_data *data, u8 reg,