chore(goldair_platinum_tower_fan): remove old timer attribute

Timer was made into an entity a long time ago, this read-only attribute
is no longer needed.

custom_components/tuya_local/devices/goldair_platinum_tower_fan.yaml

@@ -36,9 +36,6 @@ entities:
             value: true
           - dps_val: "off"
             value: false
-      - id: 6
-        type: integer
-        name: timer
   - entity: number
     translation_key: timer
     class: duration