bonding: release slaves when master removed via sysfs

Add a call to bond_release_all in the bonding netdev event
handler for the master.  This releases the slaves for the case of, e.g.,
"echo -bond0 > /sys/class/net/bonding_masters", which otherwise will spin
forever waiting for references to be released.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/bonding/bond_main.c

@@ -3401,9 +3401,7 @@ static int bond_master_netdev_event(unsigned long event, struct net_device *bond
 	case NETDEV_CHANGENAME:
 		return bond_event_changename(event_bond);
 	case NETDEV_UNREGISTER:
-		/*
-		 * TODO: remove a bond from the list?
-		 */
+		bond_release_all(event_bond->dev);
 		break;
 	default:
 		break;