Ditua aroma diffuser: correct color_mode config

- "colour" should map to "hs", not "rgb"
- remove the default of "white", if the value is not present let it default to hs based on the available dps

Discussion #3160

custom_components/tuya_local/devices/ditua_dt1522yn_aromadiffuser.yaml

@@ -63,12 +63,9 @@ entities:
           - dps_val: white
             value: white
           - dps_val: colour
-            value: rgb
+            value: hs
           - dps_val: colourful1
             value: Mood
-          - dps_val: null
-            value: white
-            hidden: true
       - id: 111
         type: integer
         name: brightness