netfilter: xtables: mark initial tables constant

The inputted table is never modified, so should be considered const.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv6/netfilter/ip6table_filter.c b/net/ipv6/netfilter/ip6table_filter.c
index 0a3ae48..6f4383a 100644
--- a/net/ipv6/netfilter/ip6table_filter.c
+++ b/net/ipv6/netfilter/ip6table_filter.c
@@ -51,7 +51,7 @@
 	.term = IP6T_ERROR_INIT,		/* ERROR */
 };
 
-static struct xt_table packet_filter = {
+static const struct xt_table packet_filter = {
 	.name		= "filter",
 	.valid_hooks	= FILTER_VALID_HOOKS,
 	.me		= THIS_MODULE,