xfrm: policy: make policy backend const

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv6/xfrm6_policy.c

@@ -289,7 +289,7 @@ static struct dst_ops xfrm6_dst_ops_template = {
 	.gc_thresh =		INT_MAX,
 };
 
-static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
+static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 	.dst_ops =		&xfrm6_dst_ops_template,
 	.dst_lookup =		xfrm6_dst_lookup,
 	.get_saddr =		xfrm6_get_saddr,