Settings: move keyguard wallpaper to system (2/2)

Change-Id: Id3bb66aa78c2e3dbd1170e74e33fcd160e5a70bb
Signed-off-by: Roman Birg <roman@cyngn.com>
cleanup imports in LockscreenStyle.java

Change-Id: I8da847b11afe94312ff736750347fe816a8eb152