iommu/amd: Unmap all mapped pages in error path of map_sg

In the error path of map_sg there is an incorrect if condition
for breaking out of the loop that searches the scatterlist
for mapped pages to unmap. Instead of breaking out of the
loop once all the pages that were mapped have been unmapped,
it will break out of the loop after it has unmapped 1 page.
Fix the condition, so it breaks out of the loop only after
all the mapped pages have been unmapped.

Fixes: 80187fd3 ("iommu/amd: Optimize map_sg and unmap_sg")
Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -2617,7 +2617,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist,
 			bus_addr  = address + s->dma_address + (j << PAGE_SHIFT);
 			iommu_unmap_page(domain, bus_addr, PAGE_SIZE);
 
-			if (--mapped_pages)
+			if (--mapped_pages == 0)
 				goto out_free_iova;
 		}
 	}