mac80211: ignore CSA to same channel

If the AP is confused and starts doing a CSA to the same channel,
just ignore that request instead of trying to act it out since it
was likely sent in error anyway.

In the case of the bug I was investigating the GO was misbehaving
and sending out a beacon with CSA IEs still included after having
actually done the channel switch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -464,6 +464,7 @@ struct ieee80211_if_managed {
 	unsigned int flags;
 
 	bool csa_waiting_bcn;
+	bool csa_ignored_same_chan;
 
 	bool beacon_crc_valid;
 	u32 beacon_crc;