Setup lock screen go back one screen at a time

SetupChooseLockGeneric no longer finishes itself when it receives a
RESULT_CANCELED result from an activity it started.

Bug: 18631770
Change-Id: I892b76847904225fe607b9406d6e76f932daa062

src/com/android/settings/SetupRedactionInterstitial.java

@@ -67,6 +67,7 @@ public class SetupRedactionInterstitial extends RedactionInterstitial
     @Override
     public void onNavigationBarCreated(SetupWizardNavBar bar) {
         SetupWizardUtils.setImmersiveMode(this, bar);
+        bar.getBackButton().setEnabled(false);
     }
 
     @Override