(Qt) Fix setting value size (#17332)

ui/drivers/qt/qt_widgets.cpp

@@ -454,7 +454,7 @@ StringComboBox::StringComboBox(rarch_setting_t *setting, QWidget *parent) :
 
 void StringComboBox::onCurrentTextChanged(const QString &text)
 {
-   strlcpy(m_value, text.toUtf8().data(), sizeof(m_value));
+   strlcpy(m_value, text.toUtf8().data(), m_setting->size);
 
    setting_generic_handle_change(m_setting);
 }