GPIO valve: add configuration schema

Add configuration schema for GPIO based valve where the valve's open
status is depicted by a GPIO. This configuration will be consumed by
ValveMonitor service which will be added to dbus-sensors repository.

Change-Id: I5f6640886a4393e403fc1714e2cd239870bae6ef
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/schemas/meson.build b/schemas/meson.build
index fb8821b..1dc345e 100644
--- a/schemas/meson.build
+++ b/schemas/meson.build
@@ -20,5 +20,6 @@
     'stepwise.json',
     'topology.json',
     'usb_port.json',
+    'valve.json',
     'virtual_sensor.json',
 ]