MAINTAINERS: Add 9p test client to section "virtio-9p"

The 9p test cases use a dedicated, lite-weight 9p client implementation
(using virtio transport) under tests/qtest/libqos/ to communicate with
QEMU's 9p server.

It's already there for a long time. Let's officially assign it to 9p
maintainers.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Message-Id: <E1ozhlV-0007BU-0g@lizzy.crudebyte.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index b270eb8..b0091d2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2053,6 +2053,7 @@
 F: fsdev/
 F: docs/tools/virtfs-proxy-helper.rst
 F: tests/qtest/virtio-9p-test.c
+F: tests/qtest/libqos/virtio-9p*
 T: git https://gitlab.com/gkurz/qemu.git 9p-next
 T: git https://github.com/cschoenebeck/qemu.git 9p.next