igb: Add support for quad port WOL and feature flags

Change igb from using a series of boolean operators to using a single flags
value that contains a number of different bit flags for all the different
features of the adapter.

This patch also adds WOL support for quad port adapters.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>