Image.java: resolve a javadoc error caused by a merge conflict

jme3-core/src/main/java/com/jme3/texture/Image.java

@@ -960,7 +960,7 @@ public class Image extends NativeObject implements Savable /*, Cloneable*/ {
     }
 
     /**
-     * @param efficientData ignored
+     * @return null
      * @deprecated This feature is no longer used by the engine
      */
     @Deprecated