uio/uio_pci_generic: don't return zero on failure path in probe()

If uio_register_device() fails in probe(), it breaks off initialization,
deallocates all resources, but returns zero.

The patch adds proper error code propagation.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/uio/uio_pci_generic.c

@@ -91,7 +91,8 @@ static int probe(struct pci_dev *pdev,
 	gdev->info.handler = irqhandler;
 	gdev->pdev = pdev;
 
-	if (uio_register_device(&pdev->dev, &gdev->info))
+	err = uio_register_device(&pdev->dev, &gdev->info);
+	if (err)
 		goto err_register;
 	pci_set_drvdata(pdev, gdev);