Restore lockdown setting

This was removed in error while adding wallet/controls options in
ag/14353975

Bug: 190800943
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.display
Change-Id: Id73a584d7016cf1e649dcbceeba4e81aaa2370cc
diff --git a/res/xml/security_lockscreen_settings.xml b/res/xml/security_lockscreen_settings.xml
index 82cb860..0e802f6 100644
--- a/res/xml/security_lockscreen_settings.xml
+++ b/res/xml/security_lockscreen_settings.xml
@@ -46,6 +46,12 @@
             android:summary="@string/owner_info_settings_summary" />
 
         <SwitchPreference
+            android:key="security_setting_lockdown_enabled"
+            android:title="@string/lockdown_settings_title"
+            android:summary="@string/lockdown_settings_summary"
+            settings:controller="com.android.settings.security.LockdownButtonPreferenceController" />
+
+        <SwitchPreference
             android:key="lockscreen_privacy_wallet_switch"
             android:title="@string/lockscreen_privacy_wallet_setting_toggle"
             android:summary="@string/lockscreen_privacy_wallet_summary"