swiotlb-xen: merge xen_unmap_single into xen_swiotlb_unmap_page

 * After this call, reads by the cpu to the buffer are guaranteed to see

 * whatever the device wrote there.

 */

static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,

			     size_t size, enum dma_data_direction dir,

			     unsigned long attrs)

static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,

		size_t size, enum dma_data_direction dir, unsigned long attrs)

{

	phys_addr_t paddr = xen_bus_to_phys(dev_addr);

		swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);

}

static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,

			    size_t size, enum dma_data_direction dir,

			    unsigned long attrs)

{

	xen_unmap_single(hwdev, dev_addr, size, dir, attrs);

}

static void

xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,

		size_t size, enum dma_data_direction dir)

	BUG_ON(dir == DMA_NONE);

	for_each_sg(sgl, sg, nelems, i)

		xen_unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir, attrs);

		xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg),

				dir, attrs);

}