sound-soc: move to dma_transfer_direction

fixup usage of dma direction by introducing dma_transfer_direction,
this patch moves asoc drivers to use new enum

Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Cc: Liam Girdwood <lrg@ti.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>