Add default branch to switch statement

Test: Existing tests pass
Change-Id: Ia35e54130deee2e447b605730807fc35fd70399f

library/main/src/com/android/setupwizardlib/util/WizardManagerHelper.java

@@ -268,6 +268,8 @@ public class WizardManagerHelper {
                     return R.style.SuwThemeMaterial_Light;
                 case THEME_MATERIAL:
                     return R.style.SuwThemeMaterial;
+                default:
+                    // fall through
             }
         }
         return defaultTheme;