vhost-user: part of virtio

vhost user is related to virtio, add it to the relevant entry.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

MAINTAINERS

@@ -694,6 +694,7 @@ virtio
 M: Michael S. Tsirkin <mst@redhat.com>
 S: Supported
 F: hw/*/virtio*
+F: net/vhost-user.c
 
 virtio-9p
 M: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>