gpio: i.MX: initialize earlier

The i.MX gpio driver doesn't have dependencies, so initialize
it in a core_initcall to have the gpio functions available earlier.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/gpio/gpio-imx.c

@@ -204,4 +204,4 @@ static int imx_gpio_add(void)
 	platform_driver_register(&imx_gpio_driver);
 	return 0;
 }
-coredevice_initcall(imx_gpio_add);
+core_initcall(imx_gpio_add);