timecounting: remove incomplete PPS support
The timecounting code has had stubs for pulse-per-second (PPS) polling
since it was imported in 2004. At this point it seems unlikely that
anyone is going to finish adding PPS support, so let's remove the stubs:
- Delete the dead tc_poll_pps() call from tc_windup().
- Remove all tc_poll_pps symbols from the kernel.
Link: https://marc.info/?l=openbsd-tech&m=167519035723210&w=2
ok miod@