cfg80211: calls nl80211_exit on error

nl80211_exit should be called in cfg80211_init if nl80211_init succeeds
but regulatory_init or create_singlethread_workqueue fails.
Signed-off-by: Junjie Mao <junjie_mao@yeah.net>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/core.c

@@ -1199,6 +1199,7 @@ static int __init cfg80211_init(void)
 	regulatory_exit();
 out_fail_reg:
 	debugfs_remove(ieee80211_debugfs_dir);
+	nl80211_exit();
 out_fail_nl80211:
 	unregister_netdevice_notifier(&cfg80211_netdev_notifier);
 out_fail_notifier: