MAINTAINERS: Add maintainer for hyperv video device

Maintainer for hyperv synthetic video device.

Signed-off-by: Deepak Rawat <drawat.floss@gmail.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210527112230.1274-3-drawat.floss@gmail.com