backlight: convert drivers/video/backlight/* to use module_platform_driver()

Convert the drivers in drivers/video/backlight/* 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>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>	[ep93xx_bl.c]
Cc: Mike Rapoport <mike@compulab.co.il>
Cc: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 8b5b2a4..b811e8f 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -207,17 +207,7 @@
 	.resume		= pwm_backlight_resume,
 };
 
-static int __init pwm_backlight_init(void)
-{
-	return platform_driver_register(&pwm_backlight_driver);
-}
-module_init(pwm_backlight_init);
-
-static void __exit pwm_backlight_exit(void)
-{
-	platform_driver_unregister(&pwm_backlight_driver);
-}
-module_exit(pwm_backlight_exit);
+module_platform_driver(pwm_backlight_driver);
 
 MODULE_DESCRIPTION("PWM based Backlight Driver");
 MODULE_LICENSE("GPL");