x86: convert gart to use is_buffer_dma_capable helper function

Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/pci-gart_64.c

@@ -214,24 +214,14 @@ static void iommu_full(struct device *dev, size_t size, int dir)
 static inline int
 need_iommu(struct device *dev, unsigned long addr, size_t size)
 {
-	u64 mask = *dev->dma_mask;
-	int high = addr + size > mask;
-	int mmu = high;
-
-	if (force_iommu)
-		mmu = 1;
-
-	return mmu;
+	return force_iommu ||
+		!is_buffer_dma_capable(*dev->dma_mask, addr, size);
 }
 
 static inline int
 nonforced_iommu(struct device *dev, unsigned long addr, size_t size)
 {
-	u64 mask = *dev->dma_mask;
-	int high = addr + size > mask;
-	int mmu = high;
-
-	return mmu;
+	return !is_buffer_dma_capable(*dev->dma_mask, addr, size);
 }
 
 /* Map a single continuous physical area into the IOMMU.