NetworkNotificationManager: remove spammy log

Test: build, flashed, booted phone.
Bug: 32198726
Change-Id: I3ac2f07c756f48653195f6198aaee4d8b3939fb5

services/core/java/com/android/server/connectivity/NetworkNotificationManager.java

@@ -221,11 +221,10 @@ public class NetworkNotificationManager {
     }
 
     public void clearNotification(int id) {
-        final String tag = tagFor(id);
         if (mNotificationTypeMap.indexOfKey(id) < 0) {
-            Slog.e(TAG, "cannot clear unknown notification with tag=" + tag);
             return;
         }
+        final String tag = tagFor(id);
         final int eventId = mNotificationTypeMap.get(id);
         if (DBG) {
             Slog.d(TAG, String.format("clearing notification tag=%s event=%s", tag,