[media] MAINTAINERS: add maintainer entry for video multiplexer v4l2 subdevice driver

Add maintainer entry for the video multiplexer v4l2 subdevice driver that
will control video bus multiplexers via the multiplexer framework.
Signed-off-by: Philip Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

MAINTAINERS

@@ -13545,6 +13545,12 @@ S:	Maintained
 F:	drivers/media/v4l2-core/videobuf2-*
 F:	include/media/videobuf2-*
 
+VIDEO MULTIPLEXER DRIVER
+M:	Philipp Zabel <p.zabel@pengutronix.de>
+L:	linux-media@vger.kernel.org
+S:	Maintained
+F:	drivers/media/platform/video-mux.c
+
 VIRTIO AND VHOST VSOCK DRIVER
 M:	Stefan Hajnoczi <stefanha@redhat.com>
 L:	kvm@vger.kernel.org