x86/amd-iommu: Use 2-level page tables for dma_ops domains

The driver now supports a dynamic number of levels for IO
page tables. This allows to reduce the number of levels for
dma_ops domains by one because a dma_ops domain has usually
an address space size between 128MB and 4G.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/kernel/amd_iommu.c

@@ -1010,7 +1010,7 @@ static struct dma_ops_domain *dma_ops_domain_alloc(struct amd_iommu *iommu)
 	dma_dom->domain.id = domain_id_alloc();
 	if (dma_dom->domain.id == 0)
 		goto free_dma_dom;
-	dma_dom->domain.mode = PAGE_MODE_3_LEVEL;
+	dma_dom->domain.mode = PAGE_MODE_2_LEVEL;
 	dma_dom->domain.pt_root = (void *)get_zeroed_page(GFP_KERNEL);
 	dma_dom->domain.flags = PD_DMA_OPS_MASK;
 	dma_dom->domain.priv = dma_dom;