iio: potentiometer: max5481: Fix alignment for DMA safety

iio: potentiometer: max5481: Fix alignment for DMA safety

[ Upstream commit ec1ac1c0e7a14657d729159ccfbea72f434bdaf1 ]

____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 <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-83-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>