IVGCVSW-5530 'Cannot run SSD Mobilenet f16/uint8 on CpuRef via ExecuteNetwork'

* Added FP16 DataType support to DetectionPostProcess
* For DetectionPostProcess layer output is always Float32 regardless of input type

Signed-off-by: Sadik Armagan <sadik.armagan@arm.com>
Change-Id: I21f63dd08f0863e9a98e105b3009bab3da1ab0c3
diff --git a/src/backends/reference/RefLayerSupport.cpp b/src/backends/reference/RefLayerSupport.cpp
index f48c120..b3feae6 100644
--- a/src/backends/reference/RefLayerSupport.cpp
+++ b/src/backends/reference/RefLayerSupport.cpp
@@ -722,10 +722,11 @@
 
     bool supported = true;
 
-    std::array<DataType,5> supportedInputTypes =
+    std::array<DataType,6> supportedInputTypes =
     {
         DataType::BFloat16,
         DataType::Float32,
+        DataType::Float16,
         DataType::QAsymmS8,
         DataType::QAsymmU8,
         DataType::QSymmS16