imx: dma: correct MXS_DMA_ALIGNMENT

imx: dma: correct MXS_DMA_ALIGNMENT

We should not hardcode MXS_DMA_ALIGNMENT to 32, since we can not guarantee
that socs' cache line size is 32 bytes.
If on chips whose cache line size is 64 bytes, error occurs:
"
NAND:  ERROR: v7_dcache_inval_range - start address is not aligned - 0xbdf1d1a0
ERROR: v7_dcache_inval_range - stop address is not aligned - 0xbdf1f4a0
ERROR: v7_dcache_inval_range - start address is not aligned - 0xbdf1d1a0
"
Align MXS_DMA_ALIGNMENT with ARCH_DMA_MINALIGN whose value is same to
CONFIG_SYS_CACHELINE_SIZE if CONFIG_SYS_CACHELINE_SIZE defined.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>