s390/dma: fix mapping_error detection

The map_page implementation of s390 returns DMA_ERROR_CODE in an error
situation. Correctly test if a mapping was erroneous (DMA_ERROR_CODE is
defined as ~0).
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/dma-mapping.h

@@ -52,7 +52,7 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 
 	if (dma_ops->mapping_error)
 		return dma_ops->mapping_error(dev, dma_addr);
-	return (dma_addr == 0UL);
+	return (dma_addr == DMA_ERROR_CODE);
 }
 
 static inline void *dma_alloc_coherent(struct device *dev, size_t size,