bonding: ARP monitor spams NETDEV_NOTIFY_PEERS notifiers

The bonding ARP monitor fails to decrement send_peer_notif, the
number of peer notifications (gratuitous ARP or ND) to be sent. This
results in a continuous series of notifications.

Correct this by decrementing the counter for each notification.
Reported-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Fixes: b0929915 ("bonding: Fix RTNL: assertion failed at net/core/rtnetlink.c for ab arp monitor")
Link: https://lore.kernel.org/netdev/b2fd4147-8f50-bebd-963a-1a3e8d1d9715@redhat.com/Tested-by: Jonathan Toppins <jtoppins@redhat.com>
Reviewed-by: Jonathan Toppins <jtoppins@redhat.com>
Link: https://lore.kernel.org/r/9400.1655407960@famineSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bonding/bond_main.c

@@ -3684,9 +3684,11 @@ static void bond_activebackup_arp_mon(struct bonding *bond)
 		if (!rtnl_trylock())
 			return;
 
-		if (should_notify_peers)
+		if (should_notify_peers) {
+			bond->send_peer_notif--;
 			call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
 						 bond->dev);
+		}
 		if (should_notify_rtnl) {
 			bond_slave_state_notify(bond);
 			bond_slave_link_notify(bond);