parisc: Fix sglist access in ccio-dma.c

This patch implements the same bug fix to ccio-dma.c as to sba_iommu.c.
It ensures that only the allocated entries of the sglist are accessed.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>

drivers/parisc/ccio-dma.c

@@ -1003,7 +1003,7 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 	ioc->usg_calls++;
 #endif
 
-	while(sg_dma_len(sglist) && nents--) {
+	while (nents && sg_dma_len(sglist)) {
 
 #ifdef CCIO_COLLECT_STATS
 		ioc->usg_pages += sg_dma_len(sglist) >> PAGE_SHIFT;
@@ -1011,6 +1011,7 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 		ccio_unmap_page(dev, sg_dma_address(sglist),
 				  sg_dma_len(sglist), direction, 0);
 		++sglist;
+		nents--;
 	}
 
 	DBG_RUN_SG("%s() DONE (nents %d)\n", __func__, nents);