Blackfin arch: fix a broken define in dma-mapping

dma_mapping_error is an actual function, so fix broken define with a
real inline stub
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

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

@@ -15,7 +15,11 @@ void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
 #define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)
 
-#define dma_mapping_error
+static inline
+int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	return 0;
+}
 
 /*
  * Map a single buffer of the indicated size for DMA in streaming mode.