bootctrl 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: I307ff530dbe6ac9133b50be3c74d2582acbe439d
diff --git a/boot_control_android.cc b/boot_control_android.cc
index 86c0a9f..e3ea66d 100644
--- a/boot_control_android.cc
+++ b/boot_control_android.cc
@@ -56,7 +56,7 @@
 }  // namespace boot_control
 
 bool BootControlAndroid::Init() {
-  module_ = IBootControl::getService("bootctrl");
+  module_ = IBootControl::getService();
   if (module_ == nullptr) {
     LOG(ERROR) << "Error getting bootctrl HIDL module.";
     return false;