iommu: Check for valid pgsize_bitmap in iommu_map/unmap

In case the page-size bitmap is zero the code path in
iommu_map and iommu_unmap is undefined. Make it defined and
return -ENODEV in this case.
Signed-off-by: Joerg Roedel <joro@8bytes.org>

drivers/iommu/iommu.c

@@ -734,7 +734,8 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova,
 	size_t orig_size = size;
 	int ret = 0;
 
-	if (unlikely(domain->ops->map == NULL))
+	if (unlikely(domain->ops->unmap == NULL ||
+		     domain->ops->pgsize_bitmap == 0UL))
 		return -ENODEV;
 
 	/* find out the minimum page size supported */
@@ -808,7 +809,8 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
 	size_t unmapped_page, unmapped = 0;
 	unsigned int min_pagesz;
 
-	if (unlikely(domain->ops->unmap == NULL))
+	if (unlikely(domain->ops->unmap == NULL ||
+		     domain->ops->pgsize_bitmap == 0UL))
 		return -ENODEV;
 
 	/* find out the minimum page size supported */