nios2: use the generic uncached segment support in dma-direct

Stop providing our own arch alloc/free hooks and just expose the segment
offset and use the generic dma-direct allocator.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>
3 files changed