Settings: disable lockscreen settings appropriately

Give visual feedback on which features are unavailable
with the new lockscreen style.

Change-Id: I05b905e9a6e48d884943156b2dedc93ceee57bc4
Signed-off-by: Roman Birg <roman@cyngn.com>
Merge branch 'cm-11.0' of git://github.com/CyanogenMod/android_packages_apps_Settings into cd-4.4