vfio: avoid possible overflow in vfio_iommu_type1_pin_pages

add parentheses to avoid possible vaddr overflow.

Fixes: a54eb55045ae ("vfio iommu type1: Add support for mediated devices")
Signed-off-by: Yan Zhao <[e-mail]>
Signed-off-by: Alex Williamson <[e-mail]>

drivers/vfio/vfio_iommu_type1.c

···
 			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)