powerpc/QE: use arch_initcall to probe QUICC Engine GPIOs

It was discussed that global arch_initcall() is preferred way to probe
QE GPIOs, so let's use it.

Signed-off-by: Anton Vorontsov <[e-mail]>
Signed-off-by: Kumar Gala <[e-mail]>

arch/powerpc/sysdev/qe_lib/gpio.c

···
  */
 
 #include <linux/kernel.h>
+#include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/io.h>
 #include <linux/of.h>
···
 	return 0;
 }
 
-void __init qe_add_gpiochips(void)
+static int __init qe_add_gpiochips(void)
 {
 	struct device_node *np;
 
···
 		kfree(qe_gc);
 		/* try others anyway */
 	}
+	return 0;
 }
+arch_initcall(qe_add_gpiochips);

include/asm-powerpc/qe.h

···
 #endif
 };
 
-extern void __init qe_add_gpiochips(void);
 extern int par_io_init(struct device_node *np);
 extern int par_io_of_config(struct device_node *np);
 #define QE_PIO_DIR_IN	2