mac80211: refuse shared key auth when WEP is unavailable

When WEP is not available, we should reject shared
key authentication because it could never succeed.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/mlme.c

@@ -2031,6 +2031,8 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 		auth_alg = WLAN_AUTH_OPEN;
 		break;
 	case NL80211_AUTHTYPE_SHARED_KEY:
+		if (IS_ERR(sdata->local->wep_tx_tfm))
+			return -EOPNOTSUPP;
 		auth_alg = WLAN_AUTH_SHARED_KEY;
 		break;
 	case NL80211_AUTHTYPE_FT: