The underlying clearWallpaper() service method demands that only a
single kind of wallpaper be specified as the target; but a recent
patch attempted to expand the client-side legacy method to apply to
all kinds of wallpaper, incorrectly. This patch corrects that client-
side code to do things properly.
Bug 30456015
Change-Id: I0a881957b881206e5eb775c6879ba90f10f9ffb0