mac80211: fix channel context iteration

During suspend/resume channel contexts might be
iterated even if they haven't been re-added to
the driver, keep track of this and skip them in
iteration. Also use the new status for sanity
checks.

Also clarify the fact that during HW restart all
contexts are iterated over (thanks Eliad.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 38e7883..2316118 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -685,6 +685,7 @@
 
 	enum ieee80211_chanctx_mode mode;
 	int refcount;
+	bool driver_present;
 
 	struct ieee80211_chanctx_conf conf;
 };