dmaengine: zynqmp_dma: cleanup after completing all descriptors

The current implementation iterates the entire done list for each
completed dma descriptor even if there are multiple completed
descriptors.

Avoid this by first moving all completed descriptors to the done list
and afterwards iterating the done list and finishing the descriptors.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Link: https://lore.kernel.org/r/20210826094742.1302009-6-m.tretter@pengutronix.de


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