[media] exynos4-is: Fix potential NULL pointer dereference

dev->of_node could be NULL. Hence check for the same and return before
dereferencing it in the subsequent error message.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

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

@@ -1504,16 +1504,17 @@ static int fimc_lite_probe(struct platform_device *pdev)
 	struct resource *res;
 	int ret;
 
+	if (!dev->of_node)
+		return -ENODEV;
+
 	fimc = devm_kzalloc(dev, sizeof(*fimc), GFP_KERNEL);
 	if (!fimc)
 		return -ENOMEM;
 
-	if (dev->of_node) {
 	of_id = of_match_node(flite_of_match, dev->of_node);
 	if (of_id)
 		drv_data = (struct flite_drvdata *)of_id->data;
 	fimc->index = of_alias_get_id(dev->of_node, "fimc-lite");
-	}
 
 	if (!drv_data || fimc->index >= drv_data->num_instances ||
 						fimc->index < 0) {