forcedeth: call vlan_mode only if hw supports vlans

If hw does not support vlans, dont call nv_vlan_mode because it has no point.
I believe that this should fix issues on older non-vlan supportive
chips (like Ingo has).

Reported-ty: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NJiri Pirko <jpirko@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/forcedeth.c

@@ -5615,7 +5615,8 @@ static int __devinit nv_probe(struct pci_dev *pci_dev, const struct pci_device_i
 		goto out_error;
 	}
 
-	nv_vlan_mode(dev, dev->features);
+	if (id->driver_data & DEV_HAS_VLAN)
+		nv_vlan_mode(dev, dev->features);
 
 	netif_carrier_off(dev);