iio: accel: bma220: Fix alignment for DMA safety

____cacheline_aligned is insufficient guarantee for non-coherent DMA.
Switch to the updated IIO_DMA_MINALIGN definition.

Fixes: bf2a5600 ("iio: accel: Add support for Bosch BMA220")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-6-jic23@kernel.org