dmaengine: ti: k3-udma: Move the TR counter calculation to helper function

Move the TR counter parameter configuration code out from the prep_memcpy
callback to a helper function to allow a generic re-usable code for other
TR based transfers.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200214091441.27535-4-peter.ujfalusi@ti.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>