MAINTAINERS: add entry for VKMS

Add myself as maintainer of VKMS driver

Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200904130605.vs5tnfhgnemnz6pt@smtp.gmail.com

MAINTAINERS

@@ -5640,6 +5640,7 @@ F:	drivers/gpu/drm/udl/
 DRM DRIVER FOR VIRTUAL KERNEL MODESETTING (VKMS)
 M:	Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
+M:	Melissa Wen <melissa.srw@gmail.com>
 R:	Haneen Mohammed <hamohammed.sa@gmail.com>
 R:	Daniel Vetter <daniel@ffwll.ch>
 L:	dri-devel@lists.freedesktop.org