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: I2bd735cff9674ec5955ae30efed27359041ed723
diff --git a/vr/1.0/default/service.cpp b/vr/1.0/default/service.cpp
index c27ceaf..22fb7d1 100644
--- a/vr/1.0/default/service.cpp
+++ b/vr/1.0/default/service.cpp
@@ -23,5 +23,5 @@
 using android::hardware::defaultPassthroughServiceImplementation;
 
 int main() {
-    return defaultPassthroughServiceImplementation<IVr>("vr");
+    return defaultPassthroughServiceImplementation<IVr>();
 }