Car HAL uses "default" service name

the getService() and registerAsService() methods of interface objects
now have default parameters of "default" for the service name. HALs
will not have to use any service name unless they want to register
more than one service.

Test: builds

Bug: 33844934

Change-Id: I1fc92a29178befc1b2232cfcc4b13058d57cd798
diff --git a/automotive/vehicle/2.0/default/VehicleService.cpp b/automotive/vehicle/2.0/default/VehicleService.cpp
index f88ce7b..95057cc 100644
--- a/automotive/vehicle/2.0/default/VehicleService.cpp
+++ b/automotive/vehicle/2.0/default/VehicleService.cpp
@@ -34,7 +34,7 @@
     configureRpcThreadpool(1, true /* callerWillJoin */);
 
     ALOGI("Registering as service...");
-    service->registerAsService("Vehicle");
+    service->registerAsService();
 
     ALOGI("Ready");
     joinRpcThreadpool();