DisplayModeDirector: make settings higher priority than app request

Applications can still set refresh rate to 90Hz even if the Peak refresh
rate setting is disabled. This prevents users disable 90Hz completely
(to preserve power for example).
Users should have the option to do so.

Fixes: 135044304
Test: Disable peak refresh rate and run an app that requests 90Hz
Change-Id: I7ab809f9bf75f91e983873b8993cf4a22010a5ea