Add name "default" as default to register service

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: make hidl_test; adb sync; adb shell;
data/native_test64/hidl_test64
Modify Nfc HAL to use default name
Run VTS test from go/vtsrun on Sensors, Vr, Nfc
Verify NFC HAL works (turn NFC on and off in Settings)

In support of b/33844934

Change-Id: Ib658a6a692780c16c751e57e05c653d031f30789
diff --git a/transport/include/hidl/LegacySupport.h b/transport/include/hidl/LegacySupport.h
index 8fd1795..18d8ba8 100644
--- a/transport/include/hidl/LegacySupport.h
+++ b/transport/include/hidl/LegacySupport.h
@@ -30,7 +30,8 @@
  * Registers passthrough service implementation.
  */
 template<class Interface>
-status_t registerPassthroughServiceImplementation(std::string name) {
+status_t registerPassthroughServiceImplementation(
+      std::string name = "default") {
     sp<Interface> service = Interface::getService(name, true /* getStub */);
 
     if (service == nullptr) {
@@ -57,7 +58,8 @@
  * Return value is exit status.
  */
 template<class Interface>
-int defaultPassthroughServiceImplementation(std::string name, size_t maxThreads = 1) {
+int defaultPassthroughServiceImplementation(std::string name = "default",
+                                            size_t maxThreads = 1) {
     configureRpcThreadpool(maxThreads, true);
     registerPassthroughServiceImplementation<Interface>(name);
     joinRpcThreadpool();