[NETFILTER]: xt_sctp: fix --chunk-types matching

xt_sctp uses an incorrect header offset when --chunk-types is used.
Signed-off-by: Jorge Matias <jorge.matias@motorola.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/xt_sctp.c

@@ -151,7 +151,7 @@ match(const struct sk_buff *skb,
 		&& SCCHECK(((ntohs(sh->dest) >= info->dpts[0]) 
 			&& (ntohs(sh->dest) <= info->dpts[1])), 
 			XT_SCTP_DEST_PORTS, info->flags, info->invflags)
-		&& SCCHECK(match_packet(skb, protoff,
+		&& SCCHECK(match_packet(skb, protoff + sizeof (sctp_sctphdr_t),
 					info->chunkmap, info->chunk_match_type,
  					info->flag_info, info->flag_count, 
 					hotdrop),