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 <[e-mail]>
Acked-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/uio/uio_pci_generic.c

···
 	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);