MIPS: ralink: Fix platform_get_irq's error checking

The platform_get_irq() function returns negative if an error occurs.
zero or positive number on success. platform_get_irq() error checking
for zero is not correct.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: john@phrozen.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17783/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ralink/timer.c

@@ -109,9 +109,9 @@ static int rt_timer_probe(struct platform_device *pdev)
 	}
 
 	rt->irq = platform_get_irq(pdev, 0);
-	if (!rt->irq) {
+	if (rt->irq < 0) {
 		dev_err(&pdev->dev, "failed to load irq\n");
-		return -ENOENT;
+		return rt->irq;
 	}
 
 	rt->membase = devm_ioremap_resource(&pdev->dev, res);