PerformanceManager : Ensure we clear calling identity

When going from perfmanager -> powermanager we need to clear the calling
identity otherwise you get :

Bad call: specified package android under uid 10031 but it is really 1000

CYNGNOS-786

Change-Id: Iacd310f56d6538b0f7a4779f89b4451f6a203c5b
(cherry picked from commit 61afdc1f)