bridge: Allow forward delay to be cfgd when STP enabled

int br_set_forward_delay(struct net_bridge *br, unsigned long val)

{

	unsigned long t = clock_t_to_jiffies(val);

	int err = -ERANGE;

	spin_lock_bh(&br->lock);

	if (br->stp_enabled != BR_NO_STP &&

	    (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))

		goto unlock;

	if (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)

		return -ERANGE;

	spin_lock_bh(&br->lock);

	__br_set_forward_delay(br, t);

	err = 0;

unlock:

	spin_unlock_bh(&br->lock);

	return err;

	return 0;

}