MIPS: BCM63xx: Fix double gpio registration.

bcm63xx_gpio_init is already called from prom_init to allow board to use
them early, so we can remove the unneeded arch_initcall.
Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
To: linux-mips@linux-mips.org
Cc: Maxime Bizon <mbizon@freebox.fr>
Patchwork: http://patchwork.linux-mips.org/patch/899/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/bcm63xx/gpio.c

@@ -130,5 +130,3 @@ int __init bcm63xx_gpio_init(void)
 
 	return gpiochip_add(&bcm63xx_gpio_chip);
 }
-
-arch_initcall(bcm63xx_gpio_init);