thunderbolt: Do not overwrite error code when domain adding fails

If the Thunderbolt domain adding fails for some reason we currently
always return -EIO instead of the real error code. To make debugging
easier return the actual error code instead.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

drivers/thunderbolt/nhi.c

@@ -1036,7 +1036,7 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		 */
 		tb_domain_put(tb);
 		nhi_shutdown(nhi);
-		return -EIO;
+		return res;
 	}
 	pci_set_drvdata(pdev, tb);