liquidio: support new firmware statistic fw_err_pki

Added support for new firmware statistic 'tx_err_pki'.

Signed-off-by: Rick Farrington <ricardo.farrington@cavium.com>
Signed-off-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>