dmaengine: ti: Add cppi5 header for K3 NAVSS/UDMA

The K3 DMA architecture uses CPPI5 (Communications Port Programming
Interface) specified descriptors over PSI-L bus within NAVSS.

The header provides helpers, macros to work with these descriptors in a
consistent way.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Link: https://lore.kernel.org/r/20191223110458.30766-8-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>