pinctrl: stm32: use builtin_platform_driver

Use builtin_platform_driver() helper to simplify the code.

Signed-off-by: Geliang Tang <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/stm32/pinctrl-stm32f429.c

···
 	},
 };
 
-static int __init stm32f429_pinctrl_init(void)
-{
-	return platform_driver_register(&stm32f429_pinctrl_driver);
-}
-device_initcall(stm32f429_pinctrl_init);
+builtin_platform_driver(stm32f429_pinctrl_driver);