Updates screen attention preference at onStart().

Screen attention preference needs to be refreshed at onStart() so that
it get updated immediately once the camera permission is revoked/granted
for the screen attention feature.

Bug: 171019472
Test: manual + atest AdaptiveSleepPreferenceControllerTest

Change-Id: If9ac68c022f10ffefde61b035bbf38ee14c02180

src/com/android/settings/display/ScreenTimeoutSettings.java

@@ -104,6 +104,7 @@ public class ScreenTimeoutSettings extends RadioButtonPickerFragment implements
     public void onStart() {
         super.onStart();
         mAdaptiveSleepPermissionController.updateVisibility();
+        mAdaptiveSleepController.updatePreference();
     }
 
     @Override