Revert "rq-stats: fixup for automatic auto-hotplug"

What was I thinking when I wrote this?

This reverts commit d190c7cf02f6047f7883e3cc6f8946721eb46907.
cpufreq: avoid merging hotplug attrs twice
rq-stats: handle stalled mpdecision

Trickster is currently leaving CPU1 online after applying settings.
This stalls mpdecision, leaveing CPU1 online indefinitely.  When this
happens, automatically migrate to auto-hotplug.

Offlining CPU1 from userspace after mpdecision stalls will wake
mpdecision and trigger the migration away from auto-hotplug.