dt-bindings: thermal: thermal-sensor: require "#thermal-sensor-cells"

This property is required for every thermal sensor as it's used when
using phandles.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210415112121.4999-1-zajec5@gmail.com

Documentation/devicetree/bindings/thermal/thermal-sensor.yaml

@@ -36,6 +36,9 @@ properties:
       containing several internal sensors.
     enum: [0, 1]
 
+required:
+  - "#thermal-sensor-cells"
+
 additionalProperties: true
 
 examples: