video: fbdev: pxafb: handle errors from pxafb_init_fbinfo() correctly

pxafb_init_fbinfo() can not only report errors caused by failed
allocations but also when the clock can't be found.

To fix this, return an error pointer instead of NULL in case of errors,
and up-chain the result.
Signed-off-by: NDaniel Mack <daniel@zonque.org>
Reviewed-by: NRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/pxafb.c

@@ -1802,14 +1802,14 @@ static struct pxafb_info *pxafb_init_fbinfo(struct device *dev,
 	fbi = devm_kzalloc(dev, sizeof(struct pxafb_info) + sizeof(u32) * 16,
 			   GFP_KERNEL);
 	if (!fbi)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	fbi->dev = dev;
 	fbi->inf = inf;
 
 	fbi->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(fbi->clk))
-		return NULL;
+		return ERR_CAST(fbi->clk);
 
 	strcpy(fbi->fb.fix.id, PXA_NAME);
 
@@ -2287,10 +2287,9 @@ static int pxafb_probe(struct platform_device *dev)
 	}
 
 	fbi = pxafb_init_fbinfo(&dev->dev, inf);
-	if (!fbi) {
-		/* only reason for pxafb_init_fbinfo to fail is kmalloc */
+	if (IS_ERR(fbi)) {
 		dev_err(&dev->dev, "Failed to initialize framebuffer device\n");
-		ret = -ENOMEM;
+		ret = PTR_ERR(fbi);
 		goto failed;
 	}