ARM: OMAP: dma: fix error return code in omap_system_dma_probe()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/dma.c

@@ -2083,6 +2083,7 @@ static int omap_system_dma_probe(struct platform_device *pdev)
 		dma_irq = platform_get_irq_byname(pdev, irq_name);
 		if (dma_irq < 0) {
 			dev_err(&pdev->dev, "failed: request IRQ %d", dma_irq);
+			ret = dma_irq;
 			goto exit_dma_lch_fail;
 		}
 		ret = setup_irq(dma_irq, &omap24xx_dma_irq);