dmaengine: mmp_pdma: fix reference count leaks in mmp_pdma_probe

The issue happens in an error handling path. If
of_dma_controller_register() fails, the function simply prints error
messages and returns error code, without decrementing the reference
count of pdev->device incremented earlier by
dma_async_device_register(), which may result in refcount leaks.

Fix it by invoking dma_async_device_unregister() before returning the
error code.
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Link: https://lore.kernel.org/r/20210911070533.3114-1-xiongx18@fudan.edu.cnSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/mmp_pdma.c

@@ -1123,6 +1123,7 @@ static int mmp_pdma_probe(struct platform_device *op)
 						 mmp_pdma_dma_xlate, pdev);
 		if (ret < 0) {
 			dev_err(&op->dev, "of_dma_controller_register failed\n");
+			dma_async_device_unregister(&pdev->device);
 			return ret;
 		}
 	}