qlcnic: Fix ethtool statistics length calculation

o Consider number of Tx queues while calculating the length of
  Tx statistics as part of ethtool stats.
o Calculate statistics lenght properly for 82xx and 83xx adapter

Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>