bonding: 802.3ad: make aggregator_identifier bond-private

aggregator_identifier is used to assign unique aggregator identifiers
to aggregators of a bond during device enslaving.

aggregator_identifier is currently a global variable that is zeroed in
bond_3ad_initialize().

This sequence will lead to duplicate aggregator identifiers for eth1 and eth3:

create bond0
change bond0 mode to 802.3ad
enslave eth0 to bond0 		//eth0 gets agg id 1
enslave eth1 to bond0 		//eth1 gets agg id 2
create bond1
change bond1 mode to 802.3ad
enslave eth2 to bond1		//aggregator_identifier is reset to 0
				//eth2 gets agg id 1
enslave eth3 to bond0 		//eth3 gets agg id 2

Fix this by making aggregator_identifier private to the bond.

Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Acked-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_3ad.h b/drivers/net/bonding/bond_3ad.h
index 13dc9d3..f4dd959 100644
--- a/drivers/net/bonding/bond_3ad.h
+++ b/drivers/net/bonding/bond_3ad.h
@@ -253,6 +253,7 @@
 struct ad_bond_info {
 	struct ad_system system;	    /* 802.3ad system structure */
 	u32 agg_select_timer;	    // Timer to select aggregator after all adapter's hand shakes
+	u16 aggregator_identifier;
 };
 
 struct ad_slave_info {