IVGCVSW-3398 Add LSTM normalization parameters to HAL 1.2

* Adding LSTM processing function in HAL 1.2 with normalization parameters
* Refactoring LSTM tests

!armnn:1608

Signed-off-by: Ferran Balaguer <ferran.balaguer@arm.com>
Change-Id: I0e00f14ef078a333e9f2f23d6278a5d92a3001d6
diff --git a/1.2/HalPolicy.hpp b/1.2/HalPolicy.hpp
index f689613..7468313 100644
--- a/1.2/HalPolicy.hpp
+++ b/1.2/HalPolicy.hpp
@@ -67,6 +67,8 @@
     static bool ConvertSpaceToDepth(const Operation& operation, const Model& model, ConversionData& data);
 
     static bool ConvertTanH(const Operation& operation, const Model& model, ConversionData& data);
+
+    static bool ConvertLstm(const Operation& operation, const Model& model, ConversionData& data);
 };
 
 } // namespace hal_1_2