Getting rid of vestigial Update method; already removed from the other

two OcrGraphics.

Change-Id: I58216b78bb45d54e03299e610aad89e98ed91464

Author: theoreticalb

visionSamples/ocr-reader/app/src/main/java/com/google/android/gms/samples/vision/ocrreader/OcrGraphic.java

@@ -73,15 +73,6 @@ public TextBlock getTextBlock() {
         return mText;
     }
 
-    /**
-     * Updates the TextBlock instance from the detection of the most recent frame.  Invalidates the
-     * relevant portions of the overlay to trigger a redraw.
-     */
-    void updateItem(TextBlock text) {
-        mText = text;
-        postInvalidate();
-    }
-
     /**
      * Checks whether a point is within the bounding box of this graphic.
      * The provided point should be relative to this graphic's containing overlay.