perf: Add support for exclude_idle attribute

Enable the perf exclude_idle event attribute to avoid waking
possilby sleeping CPUS. The counter values are updated when CPU
enters idle. If the CPU is idle when perf reads the current
event value (of an exclude idle event) then the value from
when the CPU went idle is returned.
This commit supercedes the commits below. The context for the
commits below changed too much to enable cherry-picking.
commit 573979dee2a7 ("perf: Add support for exclude_idle attribute")
commit 54f6e4ae87be ("perf: Enable updating exclude_idle events
at idle")
commit 960dbb1751f3 ("perf: Skip permission checks on kernel owned
perf events")

Change-Id: Ib554c9fe106963ec1b42e72aeaf84fc73201bbb7
Signed-off-by: Patrick Fay <pfay@codeaurora.org>