dmaengine: xilinx: xilinx_dma: Fix kernel doc about xilinx_dma_remove()

dmaengine: xilinx: xilinx_dma: Fix kernel doc about xilinx_dma_remove()

Since commit cc99582d46b4 ("dmaengine: xilinx: xilinx_dma: Convert to
platform remove callback returning void") xilinx_dma_remove() doesn't
return zero any more. As the function has no return value any more, just
drop the statement about the return value.

Reported-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231014211656.1512016-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>