Fixed a bunch of code inconsistencies

src/duskpsp/save/savedevicepsp.c

@@ -56,7 +56,7 @@ void saveDevicePSPCheckAvailability(savedevice_t *device) {
   saveDeviceFireCallback(device);
 }
 
-static errorret_t saveDevicePSPGetDataPath(
+errorret_t saveDevicePSPGetDataPath(
   char_t *dest,
   const size_t destSize
 ) {

src/duskpsp/save/savedevicepsp.h

@@ -27,6 +27,15 @@ typedef struct savedevice_s savedevice_t;
  */
 errorret_t saveDevicePSPInit(savedevice_t *device);
 
+/**
+ * Builds the absolute path to the combined save data file.
+ *
+ * @param dest The destination buffer to write the path into.
+ * @param destSize The size of the destination buffer, exc. null terminator.
+ * @return Error state if any.
+ */
+errorret_t saveDevicePSPGetDataPath(char_t *dest, const size_t destSize);
+
 /**
  * Writes the combined save data blob out to the memory stick, replacing it
  * atomically (write to a temp file, then swap it in) so a crash mid-write