setCarMode() only when car mode changes

Bug: 30604178

Fixes a bug where opa would be enabled for non-opa-enabled devices upon
orientation change.

Change-Id: I5f8f913a53f180d783ba1c6d1fab22514986847e

packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java

@@ -620,11 +620,12 @@ public class NavigationBarView extends LinearLayout {
             if (mCarMode && uiMode != Configuration.UI_MODE_TYPE_CAR) {
                 mCarMode = false;
                 uiCarModeChanged = true;
+                getHomeButton().setCarMode(mCarMode);
             } else if (uiMode == Configuration.UI_MODE_TYPE_CAR) {
                 mCarMode = true;
                 uiCarModeChanged = true;
+                getHomeButton().setCarMode(mCarMode);
             }
-            getHomeButton().setCarMode(mCarMode);
         }
         return uiCarModeChanged;
     }