intel_cstates: ignore negative time-delta values

I have no idea why this can happen or if there is a deeper problem.

Should fix #16546.

Change-Id: Ia160e293eabefae636ce4c861864c99b0aaa68db
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3717
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

intel_cstates: provide more info in panic

This should help understanding the problem in #16546, which we don't
understand how it can happen.

intel_cstates: Fix integer division inaccuracy

Integer division could have result in an out of bound substate.

intel_cstates: Computing C-state requires constant time step

kernel: Propagate scheduler modes to cpu{freq, idle} modules

kernel: Rework cpuidle module

* Create new interface for cpuidle modules (similar to the cpufreq
interface)
* Generic cpuidle module is no longer needed
* Fix and update Intel C-State module

intel_cstates: Fix integer division inaccuracy

Integer division could have result in an out of bound substate.

intel_cstates: Computing C-state requires constant time step

kernel: Propagate scheduler modes to cpu{freq, idle} modules

kernel: Rework cpuidle module

* Create new interface for cpuidle modules (similar to the cpufreq
interface)
* Generic cpuidle module is no longer needed
* Fix and update Intel C-State module