[TEST] recover tflite test (apache#2788)

Author: tqchen

tests/python/frontend/tflite/test_forward.py

@@ -14,7 +14,7 @@
 from tensorflow.python.ops import nn_ops
 from tensorflow.python.ops import array_ops
 from tensorflow.python.ops import variables
-from tensorflow.contrib.lite.python import interpreter as interpreter_wrapper
+from tensorflow.contrib import lite as interpreter_wrapper
 
 import tvm.relay.testing.tf as tf_testing