Set a mapping for missing optional hvac_action

Issue #616

custom_components/tuya_local/devices/inkbird_sousvide_cooker.yaml

@@ -28,6 +28,9 @@ primary_entity:
         - dps_val: complete
           value: idle
           icon: "mdi:pot"
+        - dps_val: null
+          value: "off"
+          icon: "mdi:pot-outline"
     - id: 103
       type: integer
       name: temperature