iio: accel: adxl355: Fix alignment for DMA safety

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

Fixes: 327a0eaf ("iio: accel: adxl355: Add triggered buffer support")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Puranjay Mohan <puranjay12@gmail.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-4-jic23@kernel.org