iio: imu: fxos8700: 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: 84e5ddd5 ("iio: imu: Add support for the FXOS8700 IMU")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Robert Jones <rjones@gateworks.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-77-jic23@kernel.org

drivers/iio/imu/fxos8700_core.c

@@ -167,7 +167,7 @@
 struct fxos8700_data {
 	struct regmap *regmap;
 	struct iio_trigger *trig;
-	__be16 buf[FXOS8700_DATA_BUF_SIZE] ____cacheline_aligned;
+	__be16 buf[FXOS8700_DATA_BUF_SIZE] __aligned(IIO_DMA_MINALIGN);
 };
 
 /* Regmap info */