mcb: Do not return zero on error path in mcb_pci_probe()

There is an error path in mcb_pci_probe() where
it returns zero instead of error code.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mcb/mcb-pci.c

@@ -51,6 +51,7 @@ static int mcb_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	priv->mapbase = pci_resource_start(pdev, 0);
 	if (!priv->mapbase) {
 		dev_err(&pdev->dev, "No PCI resource\n");
+		ret = -ENODEV;
 		goto out_disable;
 	}