dmaengine: jz4740: disable/unprepare clk if probe fails

in error path of jz4740_dma_probe(), call clk_disable_unprepare() to clean
up.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: 25ce6c35fea0 MIPS: jz4740: Remove custom DMA API
Signed-off-by: Tobias Jordan <Tobias.Jordan@elektrobit.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/dma-jz4740.c

@@ -555,7 +555,7 @@ static int jz4740_dma_probe(struct platform_device *pdev)
 
 	ret = dma_async_device_register(dd);
 	if (ret)
-		return ret;
+		goto err_clk;
 
 	irq = platform_get_irq(pdev, 0);
 	ret = request_irq(irq, jz4740_dma_irq, 0, dev_name(&pdev->dev), dmadev);
@@ -568,6 +568,8 @@ static int jz4740_dma_probe(struct platform_device *pdev)
 
 err_unregister:
 	dma_async_device_unregister(dd);
+err_clk:
+	clk_disable_unprepare(dmadev->clk);
 	return ret;
 }