IVGCVSW-1957: Improve warning message in Network::Optimize()

* Added data type to layer not supported warnign message for more clarity

Change-Id: I7a933ad32e6a0288e8dd712a7a1dea016e4bd9a2
diff --git a/src/armnn/Network.cpp b/src/armnn/Network.cpp
index 76c33ba..8e6f490 100644
--- a/src/armnn/Network.cpp
+++ b/src/armnn/Network.cpp
@@ -218,6 +218,7 @@
                 }
                 BOOST_LOG_TRIVIAL(warning) << "Layer of type " << GetLayerTypeAsCString(layer->GetType())
                                            << " is not supported on requested backend " << layer->GetComputeDevice()
+                                           << " for data type " << GetDataTypeName(dataType)
                                            << " (reason: " << reasonIfUnsupported
                                            << "), falling back to the next backend.";
             }