gpio: pxa: set initcall level to module init

gpio & pinctrl driver are used together. The pinctrl driver is already
launched before gpio driver in Makefile. So set gpio driver to module
init level. Otherwise, the sequence will be inverted.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-pxa.c

@@ -642,12 +642,7 @@ static struct platform_driver pxa_gpio_driver = {
 		.of_match_table = of_match_ptr(pxa_gpio_dt_ids),
 	},
 };
-
-static int __init pxa_gpio_init(void)
-{
-	return platform_driver_register(&pxa_gpio_driver);
-}
-postcore_initcall(pxa_gpio_init);
+module_platform_driver(pxa_gpio_driver);
 
 #ifdef CONFIG_PM
 static int pxa_gpio_suspend(void)