dmaengine: xilinx_dma: check dma_async_device_register return value

dma_async_device_register() can return non-zero error code. Add
condition to check the return value of dma_async_device_register
function and handle the error path.

Addresses-Coverity: Event check_return.
Fixes: 9cd4360d

 ("dma: Add Xilinx AXI Video Direct Memory Access Engine driver support")
Signed-off-by: Shravya Kumbham <shravya.kumbham@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/1608722462-29519-2-git-send-email-radhey.shyam.pandey@xilinx.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>