Final power management fixes for v4.14

 - Prevent the schedutil cpufreq governor from using the
   utilization of a wrong CPU in some cases which started to
   happen after one of the recent changes in it (Chris Redpath).

 - Blacklist Dell XPS13 9360 from using the Low Power S0 Idle _DSM
   interface as that causes serious issue (related to NVMe) to
   appear on one of these machines, even though the other Dells
   XPS13 9360 in somewhat different HW configurations behave
   correctly (Rafael Wysocki).
Merge branch 'pm-cpufreq-sched'

* pm-cpufreq-sched:
  cpufreq: schedutil: Examine the correct CPU when we update util