mac80211: memory leak in mesh_queue_preq()

We recently introduced a return here, but we need to call kfree
first.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mesh_hwmp.c

@@ -871,6 +871,7 @@ static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
 	if (mpath->flags & MESH_PATH_REQ_QUEUED) {
 		spin_unlock_bh(&mpath->state_lock);
 		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
+		kfree(preq_node);
 		return;
 	}