android-nn-driver getType returns the right device

* ArmnnDriver queries the options and returns CPU or GPU
  depending on which is the first backend listed in the options

* Resolves MLCE-401

Change-Id: If4e63e144507e817449f37926711fa325861b57d
Signed-off-by: Pablo Tello <pablo.tello@arm.com>
diff --git a/1.2/HalPolicy.hpp b/1.2/HalPolicy.hpp
index a348abe..0662e1b 100644
--- a/1.2/HalPolicy.hpp
+++ b/1.2/HalPolicy.hpp
@@ -16,6 +16,7 @@
 
 namespace armnn_driver
 {
+class DriverOptions;
 namespace hal_1_2
 {
 
@@ -31,6 +32,9 @@
     using ExecutionCallback         = V1_2::IExecutionCallback;
     using getSupportedOperations_cb = V1_2::IDevice::getSupportedOperations_1_2_cb;
     using ErrorStatus               = V1_0::ErrorStatus;
+    using DeviceType                = V1_2::DeviceType;
+
+    static DeviceType GetDeviceTypeFromOptions(const DriverOptions& options);
 
     static bool ConvertOperation(const Operation& operation, const Model& model, ConversionData& data);