Etop CH7100: move temperature calibration to an optional attribute

This was observed to be missing in the returned status, so cannot be used.
But leave it as an optional attribute so it can be observed if present.

custom_components/tuya_local/devices/etop_ch7100_thermostat.yaml

@@ -86,6 +86,10 @@ primary_entity:
           conditions:
             - dps_val: f
               value_redirect: current_temp_f
+    - id: 27
+      name: temperature_calibration
+      type: integer
+      optional: true
     - id: 28
       name: fan_mode
       type: string
@@ -140,16 +144,6 @@ secondary_entities:
           - dps_val: f
             value: Fahrenheit
             icon: "mdi:temperature-fahrenheit"
-  - entity: number
-    name: Temperature calibration
-    category: config
-    dps:
-      - id: 27
-        type: integer
-        name: value
-        range:
-          min: -3
-          max: 3
   - entity: sensor
     name: Current humidity
     class: humidity