Based on Android S design, we want to let user can toggle
night light in display settings page directly.
1. Use primary switch preference in xml file.
2. Add a switch toggle controler for its preference.
3. Move logic of night display preference to controler.
4. Remove the night display preference since we migrate the logic to
controller.
Test: Night display works as intented behavior.
Bug: 174964139
Change-Id: Id920033cb22b1a9dd42c77c6fc2563ddae96bfcd
010ab29eb1