Add OCP debug card host selector button interface

A new button interface class definition is added for handling OCP
debug card host selector button events.
In case of the button release event, The host selector property is
 increased up to the max host position.

Design : https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/45544

Signed-off-by: Naveen Moses <naveen.mosess@hcl.com>
Change-Id: Iec8fabb00d1daa10f587981a9c77df8a62e3c373
diff --git a/inc/gpio.hpp b/inc/gpio.hpp
index 6f0a67b..6a63056 100644
--- a/inc/gpio.hpp
+++ b/inc/gpio.hpp
@@ -21,6 +21,12 @@
 #include <string>
 #include <vector>
 
+enum class GpioState
+{
+    low,
+    high
+};
+
 // this struct has the gpio config for single gpio
 struct gpioInfo
 {