vfio: avoid possible overflow in vfio_iommu_type1_pin_pages

add parentheses to avoid possible vaddr overflow.

Fixes: a54eb550 ("vfio iommu type1: Add support for mediated devices")
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_iommu_type1.c

@@ -555,7 +555,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 			continue;
 		}
 
-		remote_vaddr = dma->vaddr + iova - dma->iova;
+		remote_vaddr = dma->vaddr + (iova - dma->iova);
 		ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],
 					     do_accounting);
 		if (ret)