cpuidle: teo: Adjust handling of very short idle times

cpuidle: teo: Adjust handling of very short idle times

If the time till the next timer event is shorter than the target
residency of the first idle state (state 0), the TEO governor does
not update its metrics for any idle states, but arguably it should
record a "hit" for idle state 0 in that case, so modify it to do
that.

Accordingly, also make it record an "early hit" for idle state 0 if
the measured idle duration is less than its target residency, which
allows one branch more to be dropped from teo_update().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>