memtrack 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; verify HAL still works

Bug: 33844934
Change-Id: Ide36b5470a393b5ed0f60fd37661dd50d0db817b
diff --git a/memtrack/1.0/default/service.cpp b/memtrack/1.0/default/service.cpp
index f705b15..f079743 100644
--- a/memtrack/1.0/default/service.cpp
+++ b/memtrack/1.0/default/service.cpp
@@ -23,5 +23,5 @@
 using android::hardware::defaultPassthroughServiceImplementation;
 
 int main() {
-    return defaultPassthroughServiceImplementation<IMemtrack>("memtrack");
+    return defaultPassthroughServiceImplementation<IMemtrack>();
 }