- accidentaly this wasn't part of the SMP merge and the implementation
remained uncomplete with the timer keeping ticking periodically
- APIC timer is set for a signel shot and restarted everytime it
expires. This way we can keep the AP's trully idle
- the timer is restarted a little later before leaving to userspace
- LAPIC_TIMER_ICR is written before LAPIC_LVTTR so the newest value is
used