iio: gyro: adxrs450: 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 tag is inaccurate but unlikely anyone will be interested in
backporting beyond that point.

Fixes: 53ac8500 ("staging:iio:adxrs450: Move header file contents to main file")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-75-jic23@kernel.org