clk: vexpress-osc: Support building as a module

Enable building the vexpress-osc clock driver as a module.

Cc: Linus Walleij <[e-mail]>
Cc: Liviu Dudau <[e-mail]>
Cc: Lorenzo Pieralisi <[e-mail]>
Cc: Michael Turquette <[e-mail]>
Cc: [e-mail]
Reviewed-by: Sudeep Holla <[e-mail]>
Reviewed-by: Stephen Boyd <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>

drivers/clk/versatile/Kconfig

···
 	  of the ARM SP810 System Controller cell.
 
 config CLK_VEXPRESS_OSC
-	bool "Clock driver for Versatile Express OSC clock generators"
+	tristate "Clock driver for Versatile Express OSC clock generators"
 	depends on VEXPRESS_CONFIG
 	select REGMAP_MMIO
 	default y if ARCH_VEXPRESS

drivers/clk/versatile/clk-vexpress-osc.c

···
 #include <linux/clkdev.h>
 #include <linux/clk-provider.h>
 #include <linux/err.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
···
 	{ .compatible = "arm,vexpress-osc", },
 	{}
 };
+MODULE_DEVICE_TABLE(of, vexpress_osc_of_match);
 
 static struct platform_driver vexpress_osc_driver = {
 	.driver	= {
···
 	},
 	.probe = vexpress_osc_probe,
 };
-
-static int __init vexpress_osc_init(void)
-{
-	return platform_driver_register(&vexpress_osc_driver);
-}
-core_initcall(vexpress_osc_init);
+module_platform_driver(vexpress_osc_driver);
+MODULE_LICENSE("GPL v2");