Convert Vehicle Property to integer

This make sense for easier extending Vehicle Hal interface
by OEMs and creating new versions.

Test: adb shell "su system /data/nativetest/android.hardware.vehicle@2.0-manager-unit-tests/android.hardware.vehicle@2.0-manager-unit-tests" ; ENABLE_TREBLE=true make vts BUILD_GOOGLE_VTS=true -j32 && vts-tradefed run commandAndExit vts --skip-all-system-status-check --primary-abi-only --skip-preconditions --module VehicleHidlTest -l INFO

Change-Id: I02415a1c180a6d24fded48a1583f7cb150419820
Fix: b/34894217
diff --git a/vehicle/2.0/default/impl/DefaultVehicleHal.h b/vehicle/2.0/default/impl/DefaultVehicleHal.h
index 15a4789..b01c963 100644
--- a/vehicle/2.0/default/impl/DefaultVehicleHal.h
+++ b/vehicle/2.0/default/impl/DefaultVehicleHal.h
@@ -40,14 +40,14 @@
 
     StatusCode set(const VehiclePropValue& propValue) override;
 
-    StatusCode subscribe(VehicleProperty property,
-                       int32_t areas,
-                       float sampleRate) {
+    StatusCode subscribe(int32_t /*property*/,
+                         int32_t /*areas*/,
+                         float /*sampleRate*/) override {
         // TODO(pavelm): implement
         return StatusCode::OK;
     }
 
-    StatusCode unsubscribe(VehicleProperty property) {
+    StatusCode unsubscribe(int32_t /*property*/) override {
         // TODO(pavelm): implement
         return StatusCode::OK;
     }