cfg80211: show interface type

This patch makes cfg80211 show the interface in the nl80211
information about a specific interface. API users are required
to keep the type updated (everything else is fairly complicated)
but you will get a warning if you fail to keep it updated.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 88cb733..d694008 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -384,6 +384,8 @@
 
 	rdev = wiphy_to_dev(dev->ieee80211_ptr->wiphy);
 
+	WARN_ON(dev->ieee80211_ptr->iftype == NL80211_IFTYPE_UNSPECIFIED);
+
 	switch (state) {
 	case NETDEV_REGISTER:
 		mutex_lock(&rdev->devlist_mtx);