SurfaceFlinger: call to changeRefreshRate on state change only

Check if Scheduler's idle timer / content detection changed before
calling to changeRefreshRate to avoid sending config changed events when
those are not neeed.

Test: scroll within calendar app and observe systraces
Bug: 130759239
Change-Id: If7bce0ac096630918decbf62c568baa5e17408f2
3 files changed