hw/virtio: add boilerplate for vhost-user-gpio device

This creates the QEMU side of the vhost-user-gpio device which connects
to the remote daemon. It is based of vhost-user-i2c code.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <5390324a748194a21bc99b1538e19761a8c64092.1641987128.git.viresh.kumar@linaro.org>
[AJB: fixes for qtest, tweaks to feature bits]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>

Message-Id: <20220802095010.3330793-13-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index e1530b5..66d519f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2098,6 +2098,13 @@
 F: include/hw/virtio/vhost-user-rng.h
 F: tools/vhost-user-rng/*
 
+vhost-user-gpio
+M: Alex Bennée <alex.bennee@linaro.org>
+R: Viresh Kumar <viresh.kumar@linaro.org>
+S: Maintained
+F: hw/virtio/vhost-user-gpio.c
+F: include/hw/virtio/vhost-user-gpio.h
+
 virtio-crypto
 M: Gonglei <arei.gonglei@huawei.com>
 S: Supported