fix the default value of predictor inputStd in android example

deploy/android_demo/app/src/main/java/com/baidu/paddle/lite/demo/ocr/Predictor.java

@@ -34,7 +34,7 @@ public class Predictor {
     protected String inputColorFormat = "BGR";
     protected long[] inputShape = new long[]{1, 3, 960};
     protected float[] inputMean = new float[]{0.485f, 0.456f, 0.406f};
-    protected float[] inputStd = new float[]{1.0f / 0.229f, 1.0f / 0.224f, 1.0f / 0.225f};
+    protected float[] inputStd = new float[]{0.229f, 0.224f, 0.225f};
     protected float scoreThreshold = 0.1f;
     protected Bitmap inputImage = null;
     protected Bitmap outputImage = null;