MAINTAINERS: Add myself to maintainers and remove Havard

MAINTAINERS: Add myself to maintainers and remove Havard

Havard is no longer working on the Nuvoton systems for a while
and won't be able to do any work on it in the future. So I'll
take over maintaining the Nuvoton system from him.

Signed-off-by: Hao Wu <wuhaotsh@google.com>
Acked-by: Havard Skinnemoen <hskinnemoen@google.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@linaro.org>
Message-id: 20230208235433.3989937-2-wuhaotsh@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>