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/rail.hpp b/phosphor-power-sequencer/src/rail.hpp
index 040eb81..d895b51 100644
--- a/phosphor-power-sequencer/src/rail.hpp
+++ b/phosphor-power-sequencer/src/rail.hpp
@@ -31,12 +31,12 @@
 class PowerSequencerDevice;
 
 /**
- * @struct GPIO
+ * @struct PgoodGPIO
  *
  * General Purpose Input/Output (GPIO) that can be read to obtain the pgood
  * status of a voltage rail.
  */
-struct GPIO
+struct PgoodGPIO
 {
     /**
      * The libgpiod line offset of the GPIO.
@@ -93,7 +93,7 @@
                   const std::optional<std::string>& presence,
                   const std::optional<uint8_t>& page, bool isPowerSupplyRail,
                   bool checkStatusVout, bool compareVoltageToLimit,
-                  const std::optional<GPIO>& gpio) :
+                  const std::optional<PgoodGPIO>& gpio) :
         name{name}, presence{presence}, page{page},
         isPsuRail{isPowerSupplyRail}, checkStatusVout{checkStatusVout},
         compareVoltageToLimit{compareVoltageToLimit}, gpio{gpio}
@@ -173,7 +173,7 @@
      *
      * @return GPIO
      */
-    const std::optional<GPIO>& getGPIO() const
+    const std::optional<PgoodGPIO>& getGPIO() const
     {
         return gpio;
     }
@@ -376,7 +376,7 @@
     /**
      * GPIO to read to determine the pgood status of the rail.
      */
-    std::optional<GPIO> gpio{};
+    std::optional<PgoodGPIO> gpio{};
 };
 
 } // namespace phosphor::power::sequencer