fix kscreenosd quicksetting

Somehow the part that enables and disabled this quicksetting got lost
while everything needed is in place. So add it, which fixes showing and
hiding this quicksettings button.

Signed-off-by: Sebastian Kügler <sebas@kde.org>

quicksettings/kscreenosd/package/contents/ui/main.qml

@@ -13,7 +13,12 @@ QS.QuickSetting {
     settingsCommand: "plasma-open-settings kcm_kscreen"
     status: i18nc("kscreen osd quicksetting", "Tap to set up")
     enabled: false
-    available: true
+    available: KScreenOSDUtil.outputs > 1
+
+    Connections {
+        target: KScreenOSDUtil
+        onOutputsChanged: kscreenosd_qs.available = (KScreenOSDUtil.outputs > 1)
+    }
 
     function toggle() {
         console.log("Showing KScreen OSD");