Load TfLite models correctly for s390x

[yasiribmcon]

Proposed changes are an extension for https://github.com/tensorflow/tensorflow/pull/60190. These changes enable string tensors in TFLite models which were generated on LE machines to be loaded successfully on BE platforms. Below test cases from TF serving test suite are getting rectified after applying this PR on s390x(BE machines):

//tensorflow_serving/servables/tensorflow:saved_model_bundle_factory_test
//tensorflow_serving/servables/tensorflow:tflite_interpreter_pool_test
//tensorflow_serving/servables/tensorflow:tflite_session_test

These changes will not cause any regression on LE/BE platforms.

[yasiribmcon]

Hi @gbaned

Could you please take a look at this PR when you have some time?

Thank you very much!