iwlegacy: don't return zero on failure paths in il4965_pci_probe()

If hardware is not ready, il4965_pci_probe() breaks off initialization,
deallocates all resources, but returns zero.
The patch adds -EIO as return value in this case.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlegacy/4965-mac.c

@@ -6556,6 +6556,7 @@ il4965_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	il4965_prepare_card_hw(il);
 	if (!il->hw_ready) {
 		IL_WARN("Failed, HW not ready\n");
+		err = -EIO;
 		goto out_iounmap;
 	}