Add fp16 support for dequantize

* Changed RefDequantizeWorkload to use Encoder/Decoder
* Added related unit tests for Cl, Neon and Ref

Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: Ic2fd4103090dd2127c6859b49305736f7b2dfb05
diff --git a/src/backends/reference/workloads/CMakeLists.txt b/src/backends/reference/workloads/CMakeLists.txt
index 7844518..29abfed 100644
--- a/src/backends/reference/workloads/CMakeLists.txt
+++ b/src/backends/reference/workloads/CMakeLists.txt
@@ -28,6 +28,8 @@
     DepthToSpace.hpp
     DetectionPostProcess.cpp
     DetectionPostProcess.hpp
+    Dequantize.cpp
+    Dequantize.hpp
     ElementwiseFunction.cpp
     ElementwiseFunction.hpp
     Encoders.hpp