net: psample: fix build error when CONFIG_INET is not enabled

Fix psample build error when CONFIG_INET is not set/enabled by
bracketing the tunnel code in #ifdef CONFIG_NET / #endif.

../net/psample/psample.c: In function ‘__psample_ip_tun_to_nlattr’:
../net/psample/psample.c:216:25: error: implicit declaration of function ‘ip_tunnel_info_opts’; did you mean ‘ip_tunnel_info_opts_set’? [-Werror=implicit-function-declaration]
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Yotam Gigi <yotam.gi@gmail.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/psample/psample.c

@@ -209,6 +209,7 @@ void psample_group_put(struct psample_group *group)
 }
 EXPORT_SYMBOL_GPL(psample_group_put);
 
+#ifdef CONFIG_INET
 static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
 			      struct ip_tunnel_info *tun_info)
 {
@@ -352,12 +353,15 @@ static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
 
 	return sum;
 }
+#endif
 
 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 			   u32 trunc_size, int in_ifindex, int out_ifindex,
 			   u32 sample_rate)
 {
+#ifdef CONFIG_INET
 	struct ip_tunnel_info *tun_info;
+#endif
 	struct sk_buff *nl_skb;
 	int data_len;
 	int meta_len;
@@ -371,9 +375,11 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 		   nla_total_size(sizeof(u32)) +	/* group_num */
 		   nla_total_size(sizeof(u32));		/* seq */
 
+#ifdef CONFIG_INET
 	tun_info = skb_tunnel_info(skb);
 	if (tun_info)
 		meta_len += psample_tunnel_meta_len(tun_info);
+#endif
 
 	data_len = min(skb->len, trunc_size);
 	if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
@@ -429,11 +435,13 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 			goto error;
 	}
 
+#ifdef CONFIG_INET
 	if (tun_info) {
 		ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
 		if (unlikely(ret < 0))
 			goto error;
 	}
+#endif
 
 	genlmsg_end(nl_skb, data);
 	genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,