IVGCVSW-8055 Add support for GELU activation function.

* Add support to CpuRef, CpuAcc and GpuAcc
* Add support to tflite parser, classic and opaque tflite delegates
* Add support to serializer and deserializer
* Add Unit tests

Signed-off-by: Teresa Charlin <teresa.charlinreyes@arm.com>
Change-Id: Ibc60ef2ef2a051e6d9af6e15d24c46316ec19de4
diff --git a/delegate/classic/src/armnn_delegate.cpp b/delegate/classic/src/armnn_delegate.cpp
index c8f57d6..6054de5 100644
--- a/delegate/classic/src/armnn_delegate.cpp
+++ b/delegate/classic/src/armnn_delegate.cpp
@@ -729,6 +729,12 @@
                                          tfLiteNode,
                                          nodeIndex,
                                          kTfLiteBuiltinGatherNd);
+        case kTfLiteBuiltinGelu:
+            return VisitActivationOperator(delegateData,
+                                           tfLiteContext,
+                                           tfLiteNode,
+                                           nodeIndex,
+                                           kTfLiteBuiltinGelu);
         case kTfLiteBuiltinGreater:
             return VisitComparisonOperator(delegateData,
                                            tfLiteContext,