These fixes/modifications should include the upper level APIs, rte_ipv4_udptcp_cksum and rte_ipv6_udptcp_cksum.
Even for ipv4 following API is more/really useful if changed to take mbufs rte_ipv4_udptcp_cksum(const struct ipv4_hdr *ipv4_hdr, const void *l4_hdr) I can not use it in present form as it requires single contiguous l4 buffer, instead using rte_raw_cksum_mbuf.
