spi: mediatek: support large PA

Add spi large PA(max=64G) support for DMA transfer.

Signed-off-by: luhua.xu <luhua.xu@mediatek.com>
Link: https://lore.kernel.org/r/1568195731-3239-4-git-send-email-luhua.xu@mediatek.com


Signed-off-by: Mark Brown <broonie@kernel.org>