ANDROID: vendor_hooks: add cpuidle event

An event that gather the idle state that the cpu attempted to enter and
actually entered is added. Through this, the idle statistics of the cpu
can be obtained and used for vendor specific algorithms or for system
analysis.

Bug: 162980647

Change-Id: I9c2491d524722042e881864488f7b3cf7e903d1e
Signed-off-by: Park Bumgyu <bumgyu.park@samsung.com>