MAINTAINERS: Self-recommended as reviewer of "Machine core"

MAINTAINERS: Self-recommended as reviewer of "Machine core"

I've built interests in the generic machine subsystem and
have also been working on projects related to this part,
self-recommand myself as a reviewer so that I can help to
review some patches familiar to me, and have a chance to
learn more continuously.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211228092221.21068-8-wangyanan55@huawei.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>