Update some wordings under the Display page

-Sleep to Screen timeout
-Styles & Wallpapers to Styles & wallpapers
-Styles & Wallpapers, sleep, font size to Styles, wallpapers, screen timeout, font size

Fixes: 130240143
Fixes: 129885706
Test: Manual View
Change-Id: Icc4f18917961773a6435a23f32d06c5061c179eb