mac80211_hwsim: fix possible memory leak in hwsim_new_radio_nl()

'hwname' is malloced in hwsim_new_radio_nl() and should be freed
before leaving from the error handling cases, otherwise it will cause
memory leak.

Fixes: ff4dd73dd2b4 ("mac80211_hwsim: check HWSIM_ATTR_RADIO_NAME length")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
static netdev_tx_t hwsim_mon_xmit(struct sk_buff *skb,
					struct net_device *dev)
{
	/* TODO: allow packet injection */
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}

static netdev_tx_t hwsim_mon_xmit(struct sk_buff *skb,
					struct net_device *dev)
{
	/* TODO: allow packet injection */
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
}
