gpu: ipu-v3: fix a possible NULL dereference

of_match_device could return NULL, and so cause a NULL pointer
dereference later.

For fixing this problem, we use of_device_get_match_data(), this will
simplify the code a little by using a standard function for
getting the match data.

Testing the return value of of_device_get_match_data is also necessary
for avoiding a second NULL deref later on devtype.
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/ipu-common.c

@@ -1355,8 +1355,6 @@ EXPORT_SYMBOL_GPL(ipu_dump);
 
 static int ipu_probe(struct platform_device *pdev)
 {
-	const struct of_device_id *of_id =
-			of_match_device(imx_ipu_dt_ids, &pdev->dev);
 	struct device_node *np = pdev->dev.of_node;
 	struct ipu_soc *ipu;
 	struct resource *res;
@@ -1364,7 +1362,9 @@ static int ipu_probe(struct platform_device *pdev)
 	int i, ret, irq_sync, irq_err;
 	const struct ipu_devtype *devtype;
 
-	devtype = of_id->data;
+	devtype = of_device_get_match_data(&pdev->dev);
+	if (!devtype)
+		return -EINVAL;
 
 	irq_sync = platform_get_irq(pdev, 0);
 	irq_err = platform_get_irq(pdev, 1);