i40e: fix configuration of RSS table with DCB

There exists a bug in the driver where the calculation of the
RSS size was not taking into account the number of traffic classes
enabled. This patch factors in the traffic classes both in
the initial configuration of the table as well as reconfiguration.

Change-ID: I34dcd345ce52faf1d6b9614bea28d450cfd5f621
Signed-off-by: Harshitha Ramamurthy <harshitha.ramamurthy@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>