launcher: show smartspace date card on Wallpaper & style

Smartspace requires a lot of information to show cards, and it shouldn't
be required to show a preview for the user on how the home screen looks
like. This changes that to always use the date card from smartspace.

Fixes: 197328474
Test: open Wallpaper & style
Change-Id: I4718a1c0397172f654b7b6b4beb96b50b3b9eeb3