ipv6: pointer math error in ip6_tnl_parse_tlv_enc_lim()

Casting is a high precedence operation but "off" and "i" are in terms of
bytes so we need to have some parenthesis here.

Fixes: fbfa743a ("ipv6: fix ip6_tnl_parse_tlv_enc_lim()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_tunnel.c

@@ -441,7 +441,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
 				if (i + sizeof(*tel) > optlen)
 					break;
 
-				tel = (struct ipv6_tlv_tnl_enc_lim *) skb->data + off + i;
+				tel = (struct ipv6_tlv_tnl_enc_lim *)(skb->data + off + i);
 				/* return index of option if found and valid */
 				if (tel->type == IPV6_TLV_TNL_ENCAP_LIMIT &&
 				    tel->length == 1)