igc: Enable NETIF_F_HW_TC flag

This assignment of the feature NETIF_F_HW_TC
occurs prior to the initial setup of the local
hw_features variable.

This ensures that NETIF_F_HW_TC are marked
as user changeable, and also enables it by
default when the driver loads.

Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>