Fix b/265054711: Settings crash on changing device orientation from battery usage page.

Bug: 265054711
Fix: 265054711
Test: presubmit
Change-Id: I585fb054980d4536bb05d4778cb439031f34232f

src/com/android/settings/fuelgauge/batteryusage/SpinnerPreference.java

@@ -66,6 +66,9 @@ public class SpinnerPreference extends Preference {
 
     @Override
     protected Parcelable onSaveInstanceState() {
+        if (mSpinner == null) {
+            return super.onSaveInstanceState();
+        }
         Log.d(TAG, "onSaveInstanceState() spinnerPosition=" + mSpinner.getSelectedItemPosition());
         return new SavedState(super.onSaveInstanceState(), mSpinner.getSelectedItemPosition());
     }