xtables: remove bogus comment on chain rename

No longer true since Patrick added the chain rename approach back in
September 2012.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/xtables.c b/iptables/xtables.c
index ca057d3..c058567 100644
--- a/iptables/xtables.c
+++ b/iptables/xtables.c
@@ -1217,7 +1217,6 @@
 		ret = nft_chain_user_del(h, chain, *table);
 		break;
 	case CMD_RENAME_CHAIN:
-		/* XXX iptables allows renaming an used chain, we don't */
 		ret = nft_chain_user_rename(h, chain, *table, newname);
 		break;
 	case CMD_SET_POLICY: