xtensa: remove DMA_ERROR_CODE

xtensa already implements the mapping_error method for its only
dma_map_ops instance.
Signed-off-by: Christoph Hellwig <hch@lst.de>

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

@@ -16,8 +16,6 @@
 #include <linux/mm.h>
 #include <linux/scatterlist.h>
 
-#define DMA_ERROR_CODE		(~(dma_addr_t)0x0)
-
 extern const struct dma_map_ops xtensa_dma_map_ops;
 
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)