Revert "Disable DND status change notification on watches."

This reverts commit 506417450b.

Reason for revert: Looking for +2 from main Android team.

Change-Id: Ieae138d8a2acce814d6ddbef2545e319edd216fe

services/core/java/com/android/server/notification/ZenModeHelper.java

@@ -1182,11 +1182,8 @@ public class ZenModeHelper {
     }
 
     private void showZenUpgradeNotification(int zen) {
-        final boolean isWatch = mContext.getPackageManager().hasSystemFeature(
-            PackageManager.FEATURE_WATCH);
         final boolean showNotification = mIsBootComplete
                 && zen != Global.ZEN_MODE_OFF
-                && !isWatch
                 && Settings.Global.getInt(mContext.getContentResolver(),
                 Settings.Global.SHOW_ZEN_UPGRADE_NOTIFICATION, 0) != 0;