dma-mapping: Implement link/unlink ranges API

Introduce new DMA APIs to perform DMA linkage of buffers
in layers higher than DMA.

In proposed API, the callers will perform the following steps.
In map path:
	if (dma_can_use_iova(...))
	    dma_iova_alloc()
	    for (page in range)
	       dma_iova_link_next(...)
	    dma_iova_sync(...)
	else
	     /* Fallback to legacy map pages */
             for (all pages)
	       dma_map_page(...)

In unmap path:
	if (dma_can_use_iova(...))
	     dma_iova_destroy()
	else
	     for (all pages)
		dma_unmap_page(...)

Reviewed-by: Christoph Hellwig <[email protected]>
Tested-by: Jens Axboe <[email protected]>
Reviewed-by: Luis Chamberlain <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Marek Szyprowski <[email protected]>

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