bus: vexpress-config: Support building as module

Enable building vexpress-config driver as a module.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/bus/Kconfig

@@ -183,7 +183,7 @@ config UNIPHIER_SYSTEM_BUS
 	  needed to use on-board devices connected to UniPhier SoCs.
 
 config VEXPRESS_CONFIG
-	bool "Versatile Express configuration bus"
+	tristate "Versatile Express configuration bus"
 	default y if ARCH_VEXPRESS
 	depends on ARM || ARM64
 	depends on OF

drivers/bus/vexpress-config.c

@@ -7,6 +7,7 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/of_device.h>
@@ -407,15 +408,12 @@ static const struct platform_device_id vexpress_syscfg_id_table[] = {
 	{ "vexpress-syscfg", },
 	{},
 };
+MODULE_DEVICE_TABLE(platform, vexpress_syscfg_id_table);
 
 static struct platform_driver vexpress_syscfg_driver = {
 	.driver.name = "vexpress-syscfg",
 	.id_table = vexpress_syscfg_id_table,
 	.probe = vexpress_syscfg_probe,
 };
-
-static int __init vexpress_syscfg_init(void)
-{
-	return platform_driver_register(&vexpress_syscfg_driver);
-}
-core_initcall(vexpress_syscfg_init);
+module_platform_driver(vexpress_syscfg_driver);
+MODULE_LICENSE("GPL v2");