Vr 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: I32806ac4ab6cf1b7c67eb61cfbc7e203c5b5b5a3

services/core/jni/com_android_server_vr_VrManagerService.cpp

@@ -38,7 +38,7 @@ static void init_native(JNIEnv* /* env */, jclass /* clazz */) {
         return;
     }
 
-    gVr = IVr::getService("vr");
+    gVr = IVr::getService();
     if (gVr == nullptr) {
         ALOGW("%s: Could not open IVr interface", __FUNCTION__);
         return;