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

This patch converts the drivers in drivers/rtc/* 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: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Ben Dooks <ben@simtec.co.uk>
Cc: John Stultz <john.stultz@linaro.org>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-ds1553.c b/drivers/rtc/rtc-ds1553.c
index 1350029..6f0a1b5 100644
--- a/drivers/rtc/rtc-ds1553.c
+++ b/drivers/rtc/rtc-ds1553.c
@@ -361,18 +361,7 @@
 	},
 };
 
-static __init int ds1553_init(void)
-{
-	return platform_driver_register(&ds1553_rtc_driver);
-}
-
-static __exit void ds1553_exit(void)
-{
-	platform_driver_unregister(&ds1553_rtc_driver);
-}
-
-module_init(ds1553_init);
-module_exit(ds1553_exit);
+module_platform_driver(ds1553_rtc_driver);
 
 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 MODULE_DESCRIPTION("Dallas DS1553 RTC driver");