inet: constify ip headers and in6_addr

Add const qualifiers to structs iphdr, ipv6hdr and in6_addr pointers
where possible, to make code intention more obvious.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_lro.c b/net/ipv4/inet_lro.c
index 47038cb..85a0f75 100644
--- a/net/ipv4/inet_lro.c
+++ b/net/ipv4/inet_lro.c
@@ -51,8 +51,8 @@
  * Basic tcp checks whether packet is suitable for LRO
  */
 
-static int lro_tcp_ip_check(struct iphdr *iph, struct tcphdr *tcph,
-			    int len, struct net_lro_desc *lro_desc)
+static int lro_tcp_ip_check(const struct iphdr *iph, const struct tcphdr *tcph,
+			    int len, const struct net_lro_desc *lro_desc)
 {
         /* check ip header: don't aggregate padded frames */
 	if (ntohs(iph->tot_len) != len)