MAINTAINERS: Patch monkey for the Hyper-V code

Now the Hyper-V code has it's own monkey on a tree!

Make it easier to manage patch flow to upper level maintainers.

Acked-by: Haiyang Zhang <haiyangz@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>