Settings: Don't show protected apps options in restricted profiles.

Change-Id: I38c2e8fd3508d360f0e23703ce6c939f02f3714e
JIRA: 4668
Issue: https://jira.cyanogenmod.org/browse/CYAN-4668
Settings: don't remove navigation bar prefs when toggling

For devices which support the KeyDisabler class, toggling the nav bar
removes the navigation bar category, but does not add it back. If a
device can have the nav bar toggled, don't remove the category, but just
disable/enable it.

Change-Id: Ie527e3eb357e4a46097257d90c07c78e61f043a9
Signed-off-by: Roman Birg <roman@cyngn.com>