ussdiface: fix the incorrect use of indexOfMethod()

The argument of indexOfMethod() is supposed to be normallized [1]. The
"const &" shouldn't be around the QString type. Having one make Qt fails
to find the method, always triggering the error code.

It has always been incorrect, but it doesn't cause a problem because the
error handling was incorrect. Commit fc1e09e ("fix error handling
logic") fixes it, thus exposing this problem.

Fixes HelloVolla/ubuntu-touch-beta-tests#38
Should also fixes the problem on PinePhone as it uses the same code, but
I can't find the filed issue.

[1] https://doc.qt.io/qt-5/qmetaobject.html#indexOfMethod

Acked-by: Alexey Andreyev <[email protected]>

ussdiface.cpp

@@ -256,7 +256,7 @@ ConnectionInterfaceUSSDAdaptor::~ConnectionInterfaceUSSDAdaptor()
 
 void ConnectionInterfaceUSSDAdaptor::Initiate(const QString &command, const QDBusMessage& dbusMessage)
 {
-    if (adaptee()->metaObject()->indexOfMethod("initiate(const QString &,ConnectionInterfaceUSSDAdaptor::InitiateContextPtr)") == -1) {
+    if (adaptee()->metaObject()->indexOfMethod("initiate(QString,ConnectionInterfaceUSSDAdaptor::InitiateContextPtr)") == -1) {
         dbusConnection().send(dbusMessage.createErrorReply(TP_QT_ERROR_NOT_IMPLEMENTED, QLatin1String("Not implemented")));
         return;
     }