[media] exynos4-is: fix error handling of irq_of_parse_and_map

Return value of irq_of_parse_and_map() is unsigned int, with 0
indicating failure, so testing for negative result never works.
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/exynos4-is/fimc-is.c

@@ -814,9 +814,9 @@ static int fimc_is_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	is->irq = irq_of_parse_and_map(dev->of_node, 0);
-	if (is->irq < 0) {
+	if (!is->irq) {
 		dev_err(dev, "no irq found\n");
-		return is->irq;
+		return -EINVAL;
 	}
 
 	ret = fimc_is_get_clocks(is);