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/pxa2xx-flash.c b/drivers/mtd/maps/pxa2xx-flash.c
index 2a25b67..274e399 100644
--- a/drivers/mtd/maps/pxa2xx-flash.c
+++ b/drivers/mtd/maps/pxa2xx-flash.c
@@ -142,18 +142,7 @@
 	.shutdown	= pxa2xx_flash_shutdown,
 };
 
-static int __init init_pxa2xx_flash(void)
-{
-	return platform_driver_register(&pxa2xx_flash_driver);
-}
-
-static void __exit cleanup_pxa2xx_flash(void)
-{
-	platform_driver_unregister(&pxa2xx_flash_driver);
-}
-
-module_init(init_pxa2xx_flash);
-module_exit(cleanup_pxa2xx_flash);
+module_platform_driver(pxa2xx_flash_driver);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net>");