wpa_supplicant 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

In support of b/33844934

Change-Id: Ib80edecf53adf442e935a2535b8cc6e2e5aefd1e
diff --git a/wifi/supplicant/1.0/vts/functional/supplicant_hidl_test_utils.cpp b/wifi/supplicant/1.0/vts/functional/supplicant_hidl_test_utils.cpp
index 3877b97..2f3405d 100644
--- a/wifi/supplicant/1.0/vts/functional/supplicant_hidl_test_utils.cpp
+++ b/wifi/supplicant/1.0/vts/functional/supplicant_hidl_test_utils.cpp
@@ -49,7 +49,7 @@
 using ::android::wifi_system::SupplicantManager;
 
 namespace {
-const char kSupplicantServiceName[] = "wpa_supplicant";
+const char kSupplicantServiceName[] = "default";
 
 // Helper function to initialize the driver and firmware to STA mode.
 void initilializeDriverAndFirmware() {