uboot-imx

mtd: nand: mxs invalidate dcache before DMA read

Follow linux dma flow:
Before DMA read, be sure to invalidate the cache over the address
range of DMA buffer to prevent cache coherency problems.
After DMA read, invalidate dcache again.

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