mtd: devices: docg3: check the return value of devm_ioremap() in the probe

The function devm_ioremap() in docg3_probe() can fail, so
its return value should be checked.

Fixes: 82402aeb ("mtd: docg3: Use devm_*() functions")
Reported-by: Hacash Robot <hacashRobot@santino.com>
Signed-off-by: William Dean <williamsukatube@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220722091644.2937953-1-williamsukatube@163.com

drivers/mtd/devices/docg3.c

@@ -1974,9 +1974,14 @@ static int __init docg3_probe(struct platform_device *pdev)
 		dev_err(dev, "No I/O memory resource defined\n");
 		return ret;
 	}
-	base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
 
 	ret = -ENOMEM;
+	base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
+	if (!base) {
+		dev_err(dev, "devm_ioremap dev failed\n");
+		return ret;
+	}
+
 	cascade = devm_kcalloc(dev, DOC_MAX_NBFLOORS, sizeof(*cascade),
 			       GFP_KERNEL);
 	if (!cascade)