bonding: fix enslavement slave link notifications

Currently, link notifications are not sent by
bond_set_slave_link_state() upon enslavement if
the slave is enslaved when up.

This happens because slave->link default init value
is 0, which is the same as BOND_LINK_UP, resulting
in bond_set_slave_link_state() ignoring this transition.

This patch sets the default value of slave->link to
BOND_LINK_NOCHANGE, assuring it will count as a state
transition and thus trigger notification logic.

Signed-off-by: Aviv Heller <avivh@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1584,6 +1584,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	}
 
 	/* check for initial state */
+	new_slave->link = BOND_LINK_NOCHANGE;
 	if (bond->params.miimon) {
 		if (bond_check_dev_link(bond, slave_dev, 0) == BMSR_LSTATUS) {
 			if (bond->params.updelay) {