ARM: dma-mapping: introduce DMA_ERROR_CODE constant

Replace all uses of ~0 with DMA_ERROR_CODE, what should make the code
easier to read.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index cb3b7c9..6a838da 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -10,6 +10,8 @@
 #include <asm-generic/dma-coherent.h>
 #include <asm/memory.h>
 
+#define DMA_ERROR_CODE	(~0)
+
 #ifdef __arch_page_to_dma
 #error Please update to __arch_pfn_to_dma
 #endif
@@ -123,7 +125,7 @@
  */
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
-	return dma_addr == ~0;
+	return dma_addr == DMA_ERROR_CODE;
 }
 
 /*