Revert "cpufreq: interactive: let's try and live without the idle notifier and rely on the timer instead. Based on @crpalmer 's patch"

This reverts commit c3a7cfc0be4f0de8839bee9c7197a4ccbaeefbf4.
Revert "[backport] sched_rt: Upstream fixes"

This reverts commit db9a9a0fc61e443284fed8cad1211b0e37a9204e.