IVGCVSW-7568 Implement Sub ElementwiseBinary operator GpuFsa

* Added support for Gpu Sub operator
* Added unit tests

Signed-off-by: John Mcloughlin <john.mcloughlin@arm.com>
Change-Id: I1efaa485772a3716e3781566843bd50bd9bab811
diff --git a/src/backends/neon/test/NeonEndToEndTests.cpp b/src/backends/neon/test/NeonEndToEndTests.cpp
index 58c55e5..37f6d38 100644
--- a/src/backends/neon/test/NeonEndToEndTests.cpp
+++ b/src/backends/neon/test/NeonEndToEndTests.cpp
@@ -177,6 +177,15 @@
     ElementwiseBinarySimpleEndToEnd<armnn::DataType::QAsymmU8>(neonDefaultBackends, BinaryOperation::SqDiff);
 }
 
+TEST_CASE("NeonSubtractionEndToEndFloat32Simple3DTest")
+{
+    ElementwiseBinarySimple3DEndToEnd<armnn::DataType::Float32>(neonDefaultBackends, BinaryOperation::Sub);
+}
+TEST_CASE("NeonSubtractionEndToEndFloat16Simple3DTest")
+{
+    ElementwiseBinarySimple3DEndToEnd<armnn::DataType::Float16>(neonDefaultBackends, BinaryOperation::Sub);
+}
+
 // Batch Mat Mul
 TEST_CASE("NeonBatchMatMulEndToEndFloat32Test")
 {