dt-bindings: vendor-prefixes: Add kobol prefix

The prefix is already used in arm/armada-388-helios4.dts.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201014200030.845759-2-uwe@kleine-koenig.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>