qt: systray: fix systray call for macos
CXX dialogs/systray/libqt_plugin_la-systray.lo
../../../../modules/gui/qt/dialogs/systray/systray.cpp:101:21: error: no member named 'updateSystrayMenu' in 'VLCMenuBar'
VLCMenuBar::updateSystrayMenu( this, p_intf );
~~~~~~~~~~~~^
../../../../modules/gui/qt/dialogs/systray/systray.cpp:101:46: error: use of undeclared identifier 'p_intf'
VLCMenuBar::updateSystrayMenu( this, p_intf );
^