fix(koiduo_water_heater): use away_mode rather than away

Water heater uses "away_mode" for the away function.

Issue #1831 comments

custom_components/tuya_local/devices/koiduo_water_heater.yaml

@@ -8,7 +8,7 @@ entities:
     dps:
       - id: 1
         type: boolean
-        name: away
+        name: away_mode
         mapping:
           - dps_val: true
             value: false