bonding: Do not call free_netdev for already registered device.

If the call to bond_create_sysfs_entry in bond_create fails, the
proper rollback is to call unregister_netdevice, not free_netdev.
Otherwise - kernel BUG at net/core/dev.c:4057!

Checked with artificial failures injected into bond_create_sysfs_entry.

Pavel's original patch modified by Jay Vosburgh to move code around
for clarity (remove goto-hopping within the unwind block).
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NJay Vosburgh <fubar@us.ibm.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/net/bonding/bond_main.c

@@ -4936,7 +4936,9 @@ int bond_create(char *name, struct bond_params *params, struct bonding **newbond
 	if (res < 0) {
 		rtnl_lock();
 		down_write(&bonding_rwsem);
-		goto out_bond;
+		bond_deinit(bond_dev);
+		unregister_netdevice(bond_dev);
+		goto out_rtnl;
 	}
 
 	return 0;