i40e: use stored base_queue value

No need to read the PCI register for the PF's base queue on every single Tx
queue enable and disable as we already have the value stored from reading
the capability features at startup.

Change-ID: Ic02fb622757742f43cb8269369c3d972d4f66555
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>