[NETFILTER]: ip6_tables: use correct nexthdr value in ipv6_find_hdr()

nexthdr is NEXTHDR_FRAGMENT, the nexthdr value from the fragment header
is hp->nexthdr.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/netfilter/ip6_tables.c

@@ -1494,7 +1494,7 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 			if (_frag_off) {
 				if (target < 0 &&
 				    ((!ipv6_ext_hdr(hp->nexthdr)) ||
-				     nexthdr == NEXTHDR_NONE)) {
+				     hp->nexthdr == NEXTHDR_NONE)) {
 					if (fragoff)
 						*fragoff = _frag_off;
 					return hp->nexthdr;