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/mesh.c b/net/wireless/mesh.c
index 8858624..d42a3fc 100644
--- a/net/wireless/mesh.c
+++ b/net/wireless/mesh.c
@@ -195,7 +195,7 @@
 	if (!err) {
 		memcpy(wdev->ssid, setup->mesh_id, setup->mesh_id_len);
 		wdev->mesh_id_len = setup->mesh_id_len;
-		wdev->channel = setup->chandef.chan;
+		wdev->chandef = setup->chandef;
 	}
 
 	return err;
@@ -244,7 +244,7 @@
 		err = rdev_libertas_set_mesh_channel(rdev, wdev->netdev,
 						     chandef->chan);
 		if (!err)
-			wdev->channel = chandef->chan;
+			wdev->chandef = *chandef;
 
 		return err;
 	}
@@ -276,7 +276,7 @@
 	err = rdev_leave_mesh(rdev, dev);
 	if (!err) {
 		wdev->mesh_id_len = 0;
-		wdev->channel = NULL;
+		memset(&wdev->chandef, 0, sizeof(wdev->chandef));
 		rdev_set_qos_map(rdev, dev, NULL);
 	}