- Do not mark CSUM_IP_CHECKED and CSUM_IP_VALID on IPv6 packets.
IPv6 does not have checksums by definition.
- Set SCTP packets csum_flags CSUM_SCTP_VALID instead of
CSUM_DATA_VALID and skip csum_data
- Set csum_data simply as 0xffff without byteswap
Pointed out by: yongari
Reviewed by: yongari, wma
Obtained from: Semihalf
Sponsored by: Cavium
Differential Revision: https://reviews.freebsd.org/D5537