feat(windcalm_fan): hide sound switch when unavailable

This was already optional, allowing devices without it to match, but the
entity was always there. Disable it when unavailable so the user doesn't
have to.

PR #5470

custom_components/tuya_local/devices/windcalm_fan.yaml

@@ -29,8 +29,17 @@ entities:
   - entity: switch
     translation_key: sound
     category: config
+    hidden: unavailable
     dps:
       - id: 66
         type: boolean
         name: switch
         optional: true
+      - id: 66
+        type: boolean
+        optional: true
+        name: available
+        mapping:
+          - dps_val: null
+            value: false
+          - value: true