MLECO-3077: Add ASR use case API

* Minor adjustments to doc strings in KWS
* Remove unused score threshold in KWS

Signed-off-by: Richard Burton <richard.burton@arm.com>
Change-Id: Ie1c5bf6f7bdbebb853b6a10cb7ba1c4a1d9a76c9
diff --git a/source/use_case/asr/include/Wav2LetterModel.hpp b/source/use_case/asr/include/Wav2LetterModel.hpp
index 55395b9..895df2b 100644
--- a/source/use_case/asr/include/Wav2LetterModel.hpp
+++ b/source/use_case/asr/include/Wav2LetterModel.hpp
@@ -36,6 +36,9 @@
         static constexpr uint32_t ms_outputRowsIdx = 2;
         static constexpr uint32_t ms_outputColsIdx = 3;
 
+        static constexpr uint32_t ms_blankTokenIdx   = 28;
+        static constexpr uint32_t ms_numMfccFeatures = 13;
+
     protected:
         /** @brief   Gets the reference to op resolver interface class. */
         const tflite::MicroOpResolver& GetOpResolver() override;