xtables: ipv6: fix wrong error if -p is used

shell$ xtables -6 -I INPUT -p tcp --dport 22 -j ACCEPT
xtables v1.4.15: -f is not valid on IPv6
Try `xtables -h' or 'xtables --help' for more information.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/xtables.c b/iptables/xtables.c
index 9c59b7d..328bc69 100644
--- a/iptables/xtables.c
+++ b/iptables/xtables.c
@@ -1214,10 +1214,6 @@
 		cs.fw6.ipv6.invflags = invflags;
 		cs.fw6.ipv6.flags = flags;
 
-		if (flags & IPT_F_FRAG)
-			xtables_error(PARAMETER_PROBLEM,
-				      "-f is not valid on IPv6");
-
 		if (is_exthdr(cs.fw6.ipv6.proto)
 		    && (cs.fw6.ipv6.invflags & XT_INV_PROTO) == 0)
 			fprintf(stderr,