video: fbdev: pxafb: fix out of memory error path

As seen by Julia, the initial allocation memory is not checked anymore
after commit "video: fbdev: pxafb: initial devicetree conversion".
Introduce back the removed test.

Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c
index 987eb8c..33b2bb3 100644
--- a/drivers/video/fbdev/pxafb.c
+++ b/drivers/video/fbdev/pxafb.c
@@ -2249,6 +2249,8 @@
 	ret = -ENOMEM;
 	pdata = dev_get_platdata(&dev->dev);
 	inf = devm_kmalloc(&dev->dev, sizeof(*inf), GFP_KERNEL);
+	if (!inf)
+		goto failed;
 
 	if (pdata) {
 		*inf = *pdata;