net-ks8842: move to dma_transfer_direction

fixup usage of dma direction by introducing dma_transfer_direction,
this patch moves net/ks8842 drivers to use new enum

Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Samuel Ortiz <sameo@linux.intel.com>