iommu/vt-d: Don't use magic number in dma_pte_superpage

Use the already defined DMA_PTE_LARGE_PAGE for testing
instead of hardcoding the value again.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9b9f28e..5d86e93 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -304,7 +304,7 @@
 
 static inline bool dma_pte_superpage(struct dma_pte *pte)
 {
-	return (pte->val & (1 << 7));
+	return (pte->val & DMA_PTE_LARGE_PAGE);
 }
 
 static inline int first_pte_in_page(struct dma_pte *pte)