skd: switch to the generic DMA API

The PCI DMA API is deprecated, switch to the generic DMA API instead.
Also make use of the dma_set_mask_and_coherent helper to easily set
the streaming an coherent DMA masks together.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>