ANDROID: idle_notifier: Add generic idle notifiers

AOSP Change-ID: Idf29cda15be151f494ff245933c12462643388d5
moved x86_64 idle notifiers as generic so that they can
be used in interactive governor.

Upstream change 8e7a7ee9 ("x86/idle: Remove idle_notifier")
removed x86_64 idle notifiers altogether. This patch add
generic idle notifiers again.

Change-Id: Iffb48a1ea0348d9ddad93df697e4743a5531fe73
Fixes: android-4.9 commit bfd2a547fc17 ("ANDROID: ARM: Call idle notifiers")
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Git-Commit: d82a8035d09bcfcac238b80ad97335167665a7c3
Git-Repo: https://android-git.linaro.org/git/kernel/linaro-android.git


Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>