pf: Remove __FBSDID() macro use

These are local additions that no longer make sense with the transition
to git.

This partially reverts a10f530f936b7b2e3a19c406ae199b91a48f34d3.

Reviewed by: kp, imp
Differential Revision: https://reviews.freebsd.org/D42687

(cherry picked from commit bbde5c0725a5b34c456b3818cc69d17f22cef9f8)