Fixed calculation error of pkt->header_size in fill_pkt_tcp_info()

Fixed calculation error of pkt->header_size in fill_pkt_tcp_info()

The data pointer has skipped vnet_hdr_len in the function of
parse_packet_early().So, we can not subtract vnet_hdr_len again
when calculating pkt->header_size in fill_pkt_tcp_info(). Otherwise,
it will cause network packet comparsion errors and greatly increase
the frequency of checkpoints.

Signed-off-by: Lei Rao <lei.rao@intel.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Lukas Straub <lukasstraub2@web.de>
Tested-by: Lukas Straub <lukasstraub2@web.de>
Signed-off-by: Jason Wang <jasowang@redhat.com>