cfg80211: remove BUG_ON usage

These really can't trigger unless somebody messes up the code,
but don't make debugging it needlessly complicated, WARN and
return instead of BUG_ON().

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index e2923a3..4bc21a2 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -149,7 +149,8 @@
 	case CFG80211_CONN_SCAN_AGAIN:
 		return cfg80211_conn_scan(wdev);
 	case CFG80211_CONN_AUTHENTICATE_NEXT:
-		BUG_ON(!rdev->ops->auth);
+		if (WARN_ON(!rdev->ops->auth))
+			return -EOPNOTSUPP;
 		wdev->conn->state = CFG80211_CONN_AUTHENTICATING;
 		return cfg80211_mlme_auth(rdev, wdev->netdev,
 					  params->channel, params->auth_type,
@@ -161,7 +162,8 @@
 	case CFG80211_CONN_AUTH_FAILED:
 		return -ENOTCONN;
 	case CFG80211_CONN_ASSOCIATE_NEXT:
-		BUG_ON(!rdev->ops->assoc);
+		if (WARN_ON(!rdev->ops->assoc))
+			return -EOPNOTSUPP;
 		wdev->conn->state = CFG80211_CONN_ASSOCIATING;
 		if (wdev->conn->prev_bssid_valid)
 			req.prev_bssid = wdev->conn->prev_bssid;