dma: import linux/dma-direction.h to consolidate enum dma_data_direction

Import include/linux/dma-direction.h from Linux 4.13-rc7 and delete
duplicated definitions of enum dma_data_direction.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

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

@@ -8,13 +8,9 @@
 #ifndef __ASM_ARM_DMA_MAPPING_H
 #define __ASM_ARM_DMA_MAPPING_H
 
-#define	dma_mapping_error(x, y)	0
+#include <linux/dma-direction.h>
 
-enum dma_data_direction {
-	DMA_BIDIRECTIONAL	= 0,
-	DMA_TO_DEVICE		= 1,
-	DMA_FROM_DEVICE		= 2,
-};
+#define	dma_mapping_error(x, y)	0
 
 static inline void *dma_alloc_coherent(size_t len, unsigned long *handle)
 {