vlan: allow creating vlan when real device is not up

There is no reason for the arbitrary restriction that device must be
up to create a vlan. This patch was added to Vyatta kernel to resolve startup
ordering issues where vlan's are created but real device was disabled.

Note: the vlan already correctly inherits the operstate from real device; so
if vlan is created and real device is marked down, the vlan is marked
down.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan.c

@@ -225,12 +225,6 @@ int vlan_check_real_dev(struct net_device *real_dev, u16 vlan_id)
 		return -EOPNOTSUPP;
 	}
 
-	/* The real device must be up and operating in order to
-	 * assosciate a VLAN device with it.
-	 */
-	if (!(real_dev->flags & IFF_UP))
-		return -ENETDOWN;
-
 	if (__find_vlan_dev(real_dev, vlan_id) != NULL)
 		return -EEXIST;