Settings: use checkbox for expanded desktop setting for devices without navbar

On those devices, there are only two settings an a checkbox would fit better.

Change-Id: I394736dacf7765f7fdda47d6d743d7479bd4de7e
Merge branch 'cm-10.1' of git://github.com/CyanogenMod/android_packages_apps_Settings into cm-10.1-n7