cfg80211: consider existing DFS interfaces

It was possible to break interface combinations in
the following way:

 combo 1: iftype = AP, num_ifaces = 2, num_chans = 2,
 combo 2: iftype = AP, num_ifaces = 1, num_chans = 1, radar = HT20

With the above interface combinations it was
possible to:

 step 1. start AP on DFS channel by matching combo 2
 step 2. start AP on non-DFS channel by matching combo 1

This was possible beacuse (step 2) did not consider
if other interfaces require radar detection.

The patch changes how cfg80211 tracks channels -
instead of channel itself now a complete chandef
is stored.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 7526a4d..780b454 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1357,7 +1357,7 @@
 		 */
 		mutex_lock_nested(&wdev_iter->mtx, 1);
 		__acquire(wdev_iter->mtx);
-		cfg80211_get_chan_state(wdev_iter, &ch, &chmode);
+		cfg80211_get_chan_state(wdev_iter, &ch, &chmode, &radar_detect);
 		wdev_unlock(wdev_iter);
 
 		switch (chmode) {