bluetooth: use dev_addr_set()

Commit 406f42fa ("net-next: When a bond have a massive amount
of VLANs...") introduced a rbtree for faster Ethernet address look
up. To maintain netdev->dev_addr in this tree we need to make all
the writes to it go through appropriate helpers.
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/bluetooth/6lowpan.c

@@ -663,6 +663,7 @@ static struct l2cap_chan *add_peer_chan(struct l2cap_chan *chan,
 static int setup_netdev(struct l2cap_chan *chan, struct lowpan_btle_dev **dev)
 {
 	struct net_device *netdev;
+	bdaddr_t addr;
 	int err;
 
 	netdev = alloc_netdev(LOWPAN_PRIV_SIZE(sizeof(struct lowpan_btle_dev)),
@@ -672,7 +673,8 @@ static int setup_netdev(struct l2cap_chan *chan, struct lowpan_btle_dev **dev)
 		return -ENOMEM;
 
 	netdev->addr_assign_type = NET_ADDR_PERM;
-	baswap((void *)netdev->dev_addr, &chan->src);
+	baswap(&addr, &chan->src);
+	__dev_addr_set(netdev, &addr, sizeof(addr));
 
 	netdev->netdev_ops = &netdev_ops;
 	SET_NETDEV_DEV(netdev, &chan->conn->hcon->hdev->dev);