Move all time resetting after suspend / resume into resettodr() and
inittodr(). This puts all policy in those routines for trades offs
between speed and accuracy. resttodr runs when ntpd says the time is
good, or when we set the time. atrtc will be enhanced to better
preserve phase in its settime routine so resettodr() will accurately
encode the phase in the RTC so when we resume we get accurate phase by
just waiting for the next second change.
Move warming up the timeounters into tc_setclock just before we call
tc_windup. This allows the apm and acpi code to be very similar.