MAINTAINERS: add maintainer to virtio-9p

As suggested by Paolo, I add myself as maintainer for virtio-9p.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Acked-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Message-id: 20151130154016.20108.79073.stgit@bahia.huguette.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

MAINTAINERS

@@ -863,6 +863,7 @@ F: net/vhost-user.c
 
 virtio-9p
 M: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+M: Greg Kurz <gkurz@linux.vnet.ibm.com>
 S: Supported
 F: hw/9pfs/
 F: fsdev/