appletalk: remove special handling code for ipddp

After commit 1dab4713 ("appletalk: remove ipddp driver") removes the
config IPDDP, there is some minor code clean-up possible in the appletalk
network layer.

Remove some code in appletalk layer after the ipddp driver is gone.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20231012063443.22368-1-lukas.bulwahn@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/appletalk/ddp.c

@@ -1284,39 +1284,6 @@ static int atalk_getname(struct socket *sock, struct sockaddr *uaddr,
 	return err;
 }
 
-#if IS_ENABLED(CONFIG_IPDDP)
-static __inline__ int is_ip_over_ddp(struct sk_buff *skb)
-{
-	return skb->data[12] == 22;
-}
-
-static int handle_ip_over_ddp(struct sk_buff *skb)
-{
-	struct net_device *dev = __dev_get_by_name(&init_net, "ipddp0");
-	struct net_device_stats *stats;
-
-	/* This needs to be able to handle ipddp"N" devices */
-	if (!dev) {
-		kfree_skb(skb);
-		return NET_RX_DROP;
-	}
-
-	skb->protocol = htons(ETH_P_IP);
-	skb_pull(skb, 13);
-	skb->dev   = dev;
-	skb_reset_transport_header(skb);
-
-	stats = netdev_priv(dev);
-	stats->rx_packets++;
-	stats->rx_bytes += skb->len + 13;
-	return netif_rx(skb);  /* Send the SKB up to a higher place. */
-}
-#else
-/* make it easy for gcc to optimize this test out, i.e. kill the code */
-#define is_ip_over_ddp(skb) 0
-#define handle_ip_over_ddp(skb) 0
-#endif
-
 static int atalk_route_packet(struct sk_buff *skb, struct net_device *dev,
 			      struct ddpehdr *ddp, __u16 len_hops, int origlen)
 {
@@ -1480,9 +1447,6 @@ static int atalk_rcv(struct sk_buff *skb, struct net_device *dev,
 		return atalk_route_packet(skb, dev, ddp, len_hops, origlen);
 	}
 
-	/* if IP over DDP is not selected this code will be optimized out */
-	if (is_ip_over_ddp(skb))
-		return handle_ip_over_ddp(skb);
 	/*
 	 * Which socket - atalk_search_socket() looks for a *full match*
 	 * of the <net, node, port> tuple.