be2net: Fix TX stats for TSO packets

TX stats update does not take into account headers which get duplicated
when the TSO packet is split into segments by HW. Fix this for both
tunneled (vxlan) and non-tunneled TSO packets.

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>