net: Make ax25_ptr depend on CONFIG_AX25

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1804,7 +1804,9 @@ struct net_device {
 	struct dn_dev __rcu     *dn_ptr;
 #endif
 	struct inet6_dev __rcu	*ip6_ptr;
+#if IS_ENABLED(CONFIG_AX25)
 	void			*ax25_ptr;
+#endif
 	struct wireless_dev	*ieee80211_ptr;
 	struct wpan_dev		*ieee802154_ptr;
 #if IS_ENABLED(CONFIG_MPLS_ROUTING)

include/net/ax25.h

@@ -318,10 +318,12 @@ void ax25_digi_invert(const ax25_digi *, ax25_digi *);
 extern ax25_dev *ax25_dev_list;
 extern spinlock_t ax25_dev_lock;
 
+#if IS_ENABLED(CONFIG_AX25)
 static inline ax25_dev *ax25_dev_ax25dev(struct net_device *dev)
 {
 	return dev->ax25_ptr;
 }
+#endif
 
 ax25_dev *ax25_addr_ax25dev(ax25_address *);
 void ax25_dev_device_up(struct net_device *);