Rename sceGuGetInit to guGetInit

It is not a sony function, so this makes sense.

Author: sharkwouter

src/gu/pspgu.h

@@ -483,7 +483,7 @@ void sceGuTerm(void);
   *
   * @return Whether the GU system has been initialized or not
 **/
-int sceGuGetInit();
+int guGetInit();
 
 /**
   * Break the display list

src/gu/sceGuInit.c

@@ -376,6 +376,6 @@ int sceGuInit(void)
 	return 0;
 }
 
-int sceGuGetInit() {
+int guGetInit() {
 	return gu_init;
 }