power: vexpress: cleanup: use builtin_platform_driver

Use the helper macro for builtin drivers taht don't do anything special
in driver init. This removes some boilerplate code.

Link: https://lore.kernel.org/r/20200527112608.3886105-3-anders.roxell@linaro.orgSigned-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/power/reset/vexpress-poweroff.c

@@ -146,9 +146,4 @@ static struct platform_driver vexpress_reset_driver = {
 		.suppress_bind_attrs = true,
 	},
 };
-
-static int __init vexpress_reset_init(void)
-{
-	return platform_driver_register(&vexpress_reset_driver);
-}
-device_initcall(vexpress_reset_init);
+builtin_platform_driver(vexpress_reset_driver);