mac80211: wait for the first beacon on the new channel after CSA

Instead of immediately reopening the queues (in case of block_tx),
calling the post_channel_switch operation and sending the
notification, wait for the first beacon on the new channel.  This
makes sure that we don't lose packets if the AP/GO is not on the new
channel yet.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a9cc491..78d6121 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -434,6 +434,8 @@
 
 	unsigned int flags;
 
+	bool csa_waiting_bcn;
+
 	bool beacon_crc_valid;
 	u32 beacon_crc;