IVGCVSW-4439: Adding Elu support to Activation

 * Added CpuRef implementation
 * Added Unit Tests
 * Added Quantizer Test
 * Enabled Tests for Neon and CL backends on fp32 only
 * Added to Serializer

Signed-off-by: David Monahan <david.monahan@arm.com>
Change-Id: Ic23e1797dbc9352b40678c389d7fe2b836b582ea
diff --git a/src/armnnSerializer/Serializer.cpp b/src/armnnSerializer/Serializer.cpp
index b43f26c..3c01842 100644
--- a/src/armnnSerializer/Serializer.cpp
+++ b/src/armnnSerializer/Serializer.cpp
@@ -46,6 +46,8 @@
             return serializer::ActivationFunction::ActivationFunction_Sqrt;
         case armnn::ActivationFunction::Square:
             return serializer::ActivationFunction::ActivationFunction_Square;
+        case armnn::ActivationFunction::Elu:
+            return serializer::ActivationFunction::ActivationFunction_Elu;
         default:
             return serializer::ActivationFunction::ActivationFunction_Sigmoid;
     }