Only update mAboveInsetsState when necessary

This CL only updates mAboveInsetsState while the z-order of a window is
changed or the display info has been updated.

This can be a step to make client compute its window frame locally.

Bug: 161810301
Bug: 175861127
Test: atest DisplayPolicyTests DisplayPolicyLayoutTests
Change-Id: Ic202ca82ae3b0aeaf4d95ba6d0847970aa9896a6