avr32: Fix GPIO initcall breakage

Add essential system devices, including GPIO controllers, automatically
at core_initcall time. This ensures that the devices are there when the
PIO driver gets initialized at postcore_initcall, fixing a bug exposed
by commit d6634db8fe1784d0a8e4e156970fec034708446e "avr32: Use
platform_driver_probe for pio platform driver".

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/arch/avr32/mach-at32ap/at32ap700x.c b/arch/avr32/mach-at32ap/at32ap700x.c
index 8c435a6..748ac68 100644
--- a/arch/avr32/mach-at32ap/at32ap700x.c
+++ b/arch/avr32/mach-at32ap/at32ap700x.c
@@ -813,7 +813,7 @@
 DEFINE_DEV(pio, 4);
 DEV_CLK(mck, pio4, pba, 14);
 
-void __init at32_add_system_devices(void)
+static int __init system_device_init(void)
 {
 	platform_device_register(&at32_pm0_device);
 	platform_device_register(&at32_intc0_device);
@@ -832,7 +832,10 @@
 	platform_device_register(&pio2_device);
 	platform_device_register(&pio3_device);
 	platform_device_register(&pio4_device);
+
+	return 0;
 }
+core_initcall(system_device_init);
 
 /* --------------------------------------------------------------------
  *  PSIF