ipv6: sr: fix non static symbol warnings

Fixes the following sparse warnings:

net/ipv6/seg6_iptunnel.c:58:5: warning:
 symbol 'nla_put_srh' was not declared. Should it be static?
net/ipv6/seg6_iptunnel.c:238:5: warning:
 symbol 'seg6_input' was not declared. Should it be static?
net/ipv6/seg6_iptunnel.c:254:5: warning:
 symbol 'seg6_output' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/seg6_iptunnel.c

@@ -55,7 +55,7 @@ static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
 	[SEG6_IPTUNNEL_SRH]	= { .type = NLA_BINARY },
 };
 
-int nla_put_srh(struct sk_buff *skb, int attrtype,
+static int nla_put_srh(struct sk_buff *skb, int attrtype,
 		       struct seg6_iptunnel_encap *tuninfo)
 {
 	struct seg6_iptunnel_encap *data;
@@ -235,7 +235,7 @@ static int seg6_do_srh(struct sk_buff *skb)
 	return 0;
 }
 
-int seg6_input(struct sk_buff *skb)
+static int seg6_input(struct sk_buff *skb)
 {
 	int err;
 
@@ -251,7 +251,7 @@ int seg6_input(struct sk_buff *skb)
 	return dst_input(skb);
 }
 
-int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct dst_entry *orig_dst = skb_dst(skb);
 	struct dst_entry *dst = NULL;