wifi: mac80211: fix memory leak in ieee80211_mgd_assoc_ml_reconf()

Free the "data" allocation before returning on this error path.

Fixes: 36e05b0 ("wifi: mac80211: Support dynamic link addition and removal")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/7ad826a7-7651-48e7-9589-7d2dc17417c2@stanley.mountain
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -10273,8 +10273,10 @@ int ieee80211_mgd_assoc_ml_reconf(struct ieee80211_sub_if_data *sdata,
 	 * on which the request was received.
 	 */
 	skb = ieee80211_build_ml_reconf_req(sdata, data, rem_links);
-	if (!skb)
-		return -ENOMEM;
+	if (!skb) {
+		err = -ENOMEM;
+		goto err_free;
+	}
 
 	if (rem_links) {
 		u16 new_dormant_links = sdata->vif.dormant_links & ~rem_links;