Rumba heater: rename "mode" to "preset_mode".

Was incorrectly named in the original config
Issue #922

custom_components/tuya_local/devices/rumba_bathroom_heater.yaml

@@ -12,7 +12,7 @@ primary_entity:
         - dps_val: true
           value: heat
     - id: 2
-      name: mode
+      name: preset_mode
       type: string
       mapping:
         - dps_val: hot