dt-bindings: ipmi: Add npcm845 compatible

Add a compatible string for Nuvoton BMC NPCM845 KCS and modify NPCM KCS
description to support all NPCM BMC SoC.

Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Message-Id: <20220717121124.154734-2-tmaimon77@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>