x86/dma/amd_gart: Use dma_direct_{alloc,free}()

gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,

		    gfp_t flag, unsigned long attrs)

{

	dma_addr_t paddr;

	unsigned long align_mask;

	struct page *page;

	if (force_iommu && dev->coherent_dma_mask > DMA_BIT_MASK(24)) {

		flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);

		page = alloc_pages(flag | __GFP_ZERO, get_order(size));

		if (!page)

			return NULL;

	void *vaddr;

		align_mask = (1UL << get_order(size)) - 1;

		paddr = dma_map_area(dev, page_to_phys(page), size,

				     DMA_BIDIRECTIONAL, align_mask);

	vaddr = dma_direct_alloc(dev, size, dma_addr, flag, attrs);

	if (!vaddr ||

	    !force_iommu || dev->coherent_dma_mask <= DMA_BIT_MASK(24))

		return vaddr;

	*dma_addr = dma_map_area(dev, virt_to_phys(vaddr), size,

			DMA_BIDIRECTIONAL, (1UL << get_order(size)) - 1);

	flush_gart();

		if (paddr != bad_dma_addr) {

			*dma_addr = paddr;

			return page_address(page);

		}

		__free_pages(page, get_order(size));

	} else

		return dma_direct_alloc(dev, size, dma_addr, flag, attrs);

	if (unlikely(*dma_addr == bad_dma_addr))

		goto out_free;

	return vaddr;

out_free:

	dma_direct_free(dev, size, vaddr, *dma_addr, attrs);

	return NULL;

}