RGBCW lights: loosen matching to not require brightness.

Quite a few bulbs seem to only report the dps relevant to the current
mode.  BrilliantSmart RGB garden lights are one example, the log and
iot portal info both only list colordata, scene and controldata dps,
without the colortemp and brightness, but according to info about the
bulbs they do support white mode with those adjustments.  Some of the
other novelty light strings and space lamp that we have support for
were like this too.

Issue #515

ACKNOWLEDGEMENTS.md

@@ -215,3 +215,4 @@ Further device support has been made with the assistance of users.  Please consi
 - [runlar](https://github.com/runlar) for assisting with support for Deltaco SH-P02E smartplugs (dual_power_monitoring_smartplugv2 without some optional features)
 - [Kannix2005](https://github.com/Kannix2005) for assisting with support for Etersky aroma diffusers.
 - [Daverover66](https://github.com/Daverover66) for assisting with support for ElectriQ PD45E dehumidifiers.
+- [ettiennegous](https://github.com/ettiennegous) for assisting with support for BrilliantSmart RGB garden lights.

custom_components/tuya_local/devices/rgbcw_lightbulb.yaml

@@ -4,6 +4,8 @@ products:
     name: Lijun smart bulb RGBCW
   - id: nh2i3k5q5aenhdq3
     name: Aubess E14 smart bulb RGBCW
+  - id: ei0cjv7ogxdgcekq
+    name: BrilliantSmart RGB garden lights
 primary_entity:
   entity: light
   dps:
@@ -25,10 +27,12 @@ primary_entity:
     - id: 22
       name: brightness
       type: integer
+      optional: true
       range:
         min: 10
         max: 1000
       mapping:
+        - dps_val: null
         - scale: 3.92
     - id: 23
       name: color_temp