dmaengine: xilinx_dma: Remove residue from channel data

There is no use of storing channel data residue field. So clean it up.
In tx_status simply pass calculated residue to dma_set_residue.

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/1571150904-3988-4-git-send-email-radhey.shyam.pandey@xilinx.com


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