mac80211: allow drivers to access IPv6 information

To be able to implement NS response offloading (in
regular operation or while in WoWLAN) drivers need
to know the IPv6 addresses assigned to interfaces.
Implement an IPv6 notifier in mac80211 to call the
driver when addresses change.

Unlike for IPv4, implement it as a callback rather
than as a list in the BSS configuration, that is
more flexible.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index b1fed54..aec1b33 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1127,6 +1127,7 @@
 	struct timer_list dynamic_ps_timer;
 	struct notifier_block network_latency_notifier;
 	struct notifier_block ifa_notifier;
+	struct notifier_block ifa6_notifier;
 
 	/*
 	 * The dynamic ps timeout configured from user space via WEXT -