mtd: convert drivers/mtd/* to use module_platform_driver()

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

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/maps/gpio-addr-flash.c b/drivers/mtd/maps/gpio-addr-flash.c
index 1ec66f0..33cce89 100644
--- a/drivers/mtd/maps/gpio-addr-flash.c
+++ b/drivers/mtd/maps/gpio-addr-flash.c
@@ -279,17 +279,7 @@
 	},
 };
 
-static int __init gpio_flash_init(void)
-{
-	return platform_driver_register(&gpio_flash_driver);
-}
-module_init(gpio_flash_init);
-
-static void __exit gpio_flash_exit(void)
-{
-	platform_driver_unregister(&gpio_flash_driver);
-}
-module_exit(gpio_flash_exit);
+module_platform_driver(gpio_flash_driver);
 
 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
 MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");