pseq: Rename GPIO struct used for pgood status

In the phosphor-power-sequencer application, the Rail class has an
optional GPIO that provides the pgood status of the rail.

Currently the GPIO information is stored in a struct named 'GPIO'. This
structure is specific to reading the pgood status of a rail using a GPIO
on the power sequencer device.

A future commit will be creating a new GPIO class that represents an
arbitrary GPIO in the system. This class will support requesting,
reading, writing, and releasing the GPIO.

To avoid a name conflict, rename the struct to PgoodGPIO, which more
clearly represents its purpose.

Tested: Ran automated tests

Change-Id: Ie13d1c77faa96faf6839e77a84d1499f7c239148
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
diff --git a/phosphor-power-sequencer/src/config_file_parser.hpp b/phosphor-power-sequencer/src/config_file_parser.hpp
index b5b54fb..15fe7ce 100644
--- a/phosphor-power-sequencer/src/config_file_parser.hpp
+++ b/phosphor-power-sequencer/src/config_file_parser.hpp
@@ -182,18 +182,18 @@
     const json& element);
 
 /**
- * Parses a JSON element containing a GPIO.
+ * Parses a JSON element containing a gpio object.
  *
- * Returns the corresponding C++ GPIO object.
+ * Returns the corresponding C++ PgoodGPIO object.
  *
  * Throws an exception if parsing fails.
  *
  * @param element JSON element
  * @param variables variables map used to expand variables in element value
- * @return GPIO object
+ * @return PgoodGPIO object
  */
-GPIO parseGPIO(const json& element,
-               const std::map<std::string, std::string>& variables);
+PgoodGPIO parseGPIO(const json& element,
+                    const std::map<std::string, std::string>& variables);
 
 /**
  * Parses a JSON element containing an i2c_interface object.