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/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 2642a41..da5bd0e 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -627,7 +627,7 @@
 	return -1;
 }
 
-static struct inet6_protocol frag_protocol =
+static const struct inet6_protocol frag_protocol =
 {
 	.handler	=	ipv6_frag_rcv,
 	.flags		=	INET6_PROTO_NOPOLICY,