be2net: Add TX completion error statistics in ethtool

HW reports TX completion errors in TX completion. This patch adds these
counters to ethtool statistics.

Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>