mac80211_hwsim: unregister genetlink family properly

During hwsim_init_netlink(), we should call genl_unregister_family()
if failed on netlink_register_notifier() since the genetlink is
already registered.

Signed-off-by: Su Kang Yin <cantona@cantona.net>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -3121,8 +3121,10 @@ static int hwsim_init_netlink(void)
 		goto failure;
 
 	rc = netlink_register_notifier(&hwsim_netlink_notifier);
-	if (rc)
+	if (rc) {
+		genl_unregister_family(&hwsim_genl_family);
 		goto failure;
+	}
 
 	return 0;