MAINTAINERS: Add Zenghui Yu as a KVM/arm64 reviewer

Zenghui has been around for quite some time, and has been instrumental
in reviewing the GICv4/4.1 KVM support. I'm delighted that he's agreed
to help with the patch review in a more official capacity!

Acked-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230103123933.3234865-1-maz@kernel.org