4431 igb support for I354
4616 igb has uninitialized kstats
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Rafael Vanoni <rafael.vanoni@pluribusnetworks.com>
Reviewed by: Michael Speer <michael.speer@pluribusnetworks.com>
Approved by: Robert Mustacchi <rm@joyent.com>