Update daily /usr/ports on FreeBSD servers

Summary:
This feature has been removed in recent FreeBSD version
from the periodic task system.

As such, on Windriver, despite the option is configured in periodic,
per 75f1094b, the ports tree hasn't been updated since February.

Test Plan: Ensure portsnap auto run after the change is applied to WindRiver

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2374