dt-bindings: Add vendor prefix for ProBox2

PROBOX2 is a TV box brand by Hong Kong based online reseller W2COMP
Company Limited.

Cc: support@probox2.com
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -263,6 +263,7 @@ plathome	Plat'Home Co., Ltd.
 plda	PLDA
 poslab	Poslab Technology Co., Ltd.
 powervr	PowerVR (deprecated, use img)
+probox2	PROBOX2 (by W2COMP Co., Ltd.)
 pulsedlight	PulsedLight, Inc
 qca	Qualcomm Atheros, Inc.
 qcom	Qualcomm Technologies, Inc