Revert "Revert "Disable extra CPUs during Nanobench""

This reverts commit 43307c09b97c5a5c5174f0c4ccb79bdaf3ebf557.

Reason for revert: Fixed this time.  Echo 1 > already online cpu
returns exit code 1, which makes python over-react.

Original change's description:
> Revert "Disable extra CPUs during Nanobench"
>
> This reverts commit 32af335e7abbf562dad8f1bd21bb013610b8b021.
>
> Reason for revert: many unhappy android bots
>
> Original change's description:
> > Disable extra CPUs during Nanobench
> >
> > The previous experiment revealed that nanobench can
> > run on any of the online CPUs, so rather than put
> > the ones we don't need/want into powersave mode, just
> > disable them.
> >
> > Maybe in the future we can run CPU tests on the big
> > or LITTLE cpus to get perf data on higher end or
> > lower end cpus, but only if we get very stable
> > results from this.
> >
> > Bug: skia:7378
> > Change-Id: I057513a691093e7f73c0f5790e17fab1a5ec0bc4
> > Reviewed-on: https://skia-review.googlesource.com/84820
> > Reviewed-by: Kevin Lubick <kjlubick@google.com>
> > Commit-Queue: Kevin Lubick <kjlubick@google.com>
>
> TBR=borenet@google.com,mtklein@google.com,kjlubick@google.com
>
> Change-Id: I23c37a6bde631e95f0b4ae7277ec8fcf325a00e9
> Bug: skia:7378
> Reviewed-on: https://skia-review.googlesource.com/84921
> Reviewed-by: Mike Klein <mtklein@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>

No-Tree-Checks: true
Change-Id: Ie7f0a3dc6ba55c124c796aba16a0f0497f285f3a
Bug: skia:7378
Reviewed-on: https://skia-review.googlesource.com/84865
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
24 files changed