net: constify struct inet6_protocol

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 6a4b190..bb280e6 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -949,7 +949,7 @@
 	return sctp_rcv(skb) ? -1 : 0;
 }
 
-static struct inet6_protocol sctpv6_protocol = {
+static const struct inet6_protocol sctpv6_protocol = {
 	.handler      = sctp6_rcv,
 	.err_handler  = sctp_v6_err,
 	.flags        = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,