Move toggling of kernel idle timer to SF

Idle timer is toggled from the SF code using the following logic:
- If the device policy refresh rate min = max, we turn off the timer.
- If the device policy refresh rate min > the device min,
  we turn off the timer.
- Do not toggle the timer if deviceMin == policyMin.
- Timer is on in all other cases.

Bug: 140204874
Bug: 158012424
Bug: 145561154
Test: atest SurfaceFlinger_test
Test: atest libsurfaceflinger_unittest
Test: Select force 90hz through Developer Settings. Toggles timer off.
Test: Low brightness zone. Toggles timer off.
Change-Id: I9858765861a3b13e11c3930be8f77d85dae6c0c0