Merge branch 'for-rmk/perf' of git://git.kernel.org/pub/scm/linux/kernel/git/will...

There's quite a lot here, most of it from Mark Rutland, who has been
working on big.LITTLE PMU support for a while now. His work also brings
us significantly closer to moving the bulk of the CPU PMU driver out
into drivers/, where it can be shared with arm64.

As part of this work, there is a small patch to perf/core, which has
been Acked-by PeterZ and doesn't conflict with tip/perf/core at present.
I've kept that patch on a separate branch, merged in here, so that the
tip guys can pull it too if any unexpected issues crop up.

Please note that there is a conflict with mainline, since we remove
perf_event_cpu.c. The correct resolution is also to remove the file,
since the changes there are already reflected in the rework (and this
resolution is already included in linux-next).