dt-bindings: input: exc3000: support power supply regulators

Add power supply regulator support to the exc3000 devices.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230707131042.10795-1-mike.looijmans@topic.nlSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/eeti,exc3000.yaml

@@ -24,6 +24,8 @@ properties:
     maxItems: 1
   reset-gpios:
     maxItems: 1
+  vdd-supply:
+    description: Power supply regulator for the chip
   touchscreen-size-x: true
   touchscreen-size-y: true
   touchscreen-inverted-x: true