ipv6: mark address parameters of udp_tunnel6_xmit_skb() as const

The function doesn't modify the addresses passed as input, mark them
as 'const' to make that clear.
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Link: https://lore.kernel.org/r/20230924153014.786962-1-b.galvani@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

include/net/udp_tunnel.h

@@ -154,8 +154,9 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
 
 int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 			 struct sk_buff *skb,
-			 struct net_device *dev, struct in6_addr *saddr,
-			 struct in6_addr *daddr,
+			 struct net_device *dev,
+			 const struct in6_addr *saddr,
+			 const struct in6_addr *daddr,
 			 __u8 prio, __u8 ttl, __be32 label,
 			 __be16 src_port, __be16 dst_port, bool nocheck);
 

net/ipv6/ip6_udp_tunnel.c

@@ -75,8 +75,9 @@ EXPORT_SYMBOL_GPL(udp_sock_create6);
 
 int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 			 struct sk_buff *skb,
-			 struct net_device *dev, struct in6_addr *saddr,
-			 struct in6_addr *daddr,
+			 struct net_device *dev,
+			 const struct in6_addr *saddr,
+			 const struct in6_addr *daddr,
 			 __u8 prio, __u8 ttl, __be32 label,
 			 __be16 src_port, __be16 dst_port, bool nocheck)
 {