Rename the wording for "Wallpaper" under About

In order to improve the order in the search result
between "Wallpapers attributions" and "Wallpaper & style",
We should rename the wording here, and I think "Wallpaper"
is confused under About page.

Test: See the order in the search result list.
Fix: 201359802
Change-Id: I2b50703a7e4bbffd0649a60f7bc2c463f6877fba