QOfonoService: use Q_SLOTS

The rest of the code uses Q_SIGNALS, even Q_EMIT, so be consistent,
if nothing else.

Change-Id: I6441d0a630e7b592d15431c2b9ff4398223bbe9c
Reviewed-by: Valerio Valerio <valerio.valerio@jollamobile.com>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

src/plugins/bearer/connman/qofonoservice_linux_p.h

@@ -159,7 +159,7 @@ private:
     QVariantMap propertiesMap;
     QVariant getProperty(const QString &);
     QStringList contextList;
-private slots:
+private Q_SLOTS:
     void propertyChanged(const QString &, const QDBusVariant &value);
 };