cfg80211: track monitor channel

Make it even more obvious we support single
monitor channel. This will allow us to remove
.get_channel.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 019401b..434c56b 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -82,6 +82,7 @@
 				 int freq, enum nl80211_channel_type chantype)
 {
 	struct ieee80211_channel *chan;
+	int err;
 
 	if (!rdev->ops->set_monitor_channel)
 		return -EOPNOTSUPP;
@@ -92,7 +93,13 @@
 	if (!chan)
 		return -EINVAL;
 
-	return rdev->ops->set_monitor_channel(&rdev->wiphy, chan, chantype);
+	err = rdev->ops->set_monitor_channel(&rdev->wiphy, chan, chantype);
+	if (!err) {
+		rdev->monitor_channel = chan;
+		rdev->monitor_channel_type = chantype;
+	}
+
+	return err;
 }
 
 void