Qt: prepare for removal of deprecated GUI settings

If you remove a custom name and already had a deprecated name before, you'll never get rid of it.
This applies to all of the deprecated settings.

rpcs3/rpcs3qt/settings.cpp

@@ -39,9 +39,9 @@ void settings::RemoveValue(const QString& key, const QString& name)
 	}
 }
 
-QVariant settings::GetValue(const gui_save& entry) const
+void settings::RemoveValue(const gui_save& entry)
 {
-	return m_settings ? m_settings->value(entry.key + "/" + entry.name, entry.def) : entry.def;
+	RemoveValue(entry.key, entry.name);
 }
 
 QVariant settings::GetValue(const QString& key, const QString& name, const QVariant& def) const
@@ -49,6 +49,11 @@ QVariant settings::GetValue(const QString& key, const QString& name, const QVari
 	return m_settings ? m_settings->value(key + "/" + name, def) : def;
 }
 
+QVariant settings::GetValue(const gui_save& entry) const
+{
+	return GetValue(entry.key, entry.name, entry.def);
+}
+
 QVariant settings::List2Var(const q_pair_list& list)
 {
 	QByteArray ba;