ARM: ixp4xx: Drop custom DMA coherency and bouncing

The new PCI driver does not need any of this stuff, so just
drop it.

Cc: iommu@lists.linux-foundation.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220211223238.648934-12-linus.walleij@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>