TTY: serial: convert drivers/tty/serial/* to use module_platform_driver()

This patch converts the drivers in drivers/tty/serial/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jamie Iles <jamie@jamieiles.com>
Cc: Yoichi Yuasa <yuasa@linux-mips.org>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/tty/serial/vr41xx_siu.c b/drivers/tty/serial/vr41xx_siu.c
index 3beb6ab..83148e7 100644
--- a/drivers/tty/serial/vr41xx_siu.c
+++ b/drivers/tty/serial/vr41xx_siu.c
@@ -961,18 +961,7 @@
 	},
 };
 
-static int __init vr41xx_siu_init(void)
-{
-	return platform_driver_register(&siu_device_driver);
-}
-
-static void __exit vr41xx_siu_exit(void)
-{
-	platform_driver_unregister(&siu_device_driver);
-}
-
-module_init(vr41xx_siu_init);
-module_exit(vr41xx_siu_exit);
+module_platform_driver(siu_device_driver);
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:SIU");