m32r: remove DMA_ERROR_CODE

dma-noop is the only dma_mapping_ops instance for m32r and does not return
errors.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

arch/m32r/include/asm/dma-mapping.h

@@ -8,8 +8,6 @@
 #include <linux/dma-debug.h>
 #include <linux/io.h>
 
-#define DMA_ERROR_CODE (~(dma_addr_t)0x0)
-
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
 	return &dma_noop_ops;