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>

include/linux/dma-direction.h

@@ -0,0 +1,13 @@
+#ifndef _LINUX_DMA_DIRECTION_H
+#define _LINUX_DMA_DIRECTION_H
+/*
+ * These definitions mirror those in pci.h, so they can be used
+ * interchangeably with their PCI_ counterparts.
+ */
+enum dma_data_direction {
+	DMA_BIDIRECTIONAL = 0,
+	DMA_TO_DEVICE = 1,
+	DMA_FROM_DEVICE = 2,
+	DMA_NONE = 3,
+};
+#endif