Easy constant refactor in ReactEventEmitter

Summary:
This is a easy change in ReactEventEmitter that refactors the TAG used by this class to log events.
This is a follow up of D17422611

Reviewed By: makovkastar

Differential Revision: D17437034

fbshipit-source-id: 9974a244b24b04315c6a328696954b7acf7efbfd

ReactAndroid/src/main/java/com/facebook/react/uimanager/events/ReactEventEmitter.java

@@ -20,7 +20,7 @@
 
 public class ReactEventEmitter implements RCTEventEmitter {
 
-  private static final String TAG = ReactEventEmitter.class.getSimpleName();
+  private static final String TAG = "ReactEventEmitter";
 
   private final SparseArray<RCTEventEmitter> mEventEmitters = new SparseArray<>();