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>