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

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

Cc: Donggeun Kim <dg77.kim@samsung.com>
Cc: Simon Guinot <sguinot@lacie.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Ben Dooks <ben@simtec.co.uk>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: J Keerthy <j-keerthy@ti.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
diff --git a/drivers/hwmon/gpio-fan.c b/drivers/hwmon/gpio-fan.c
index 89aa9fb..9ba38f3 100644
--- a/drivers/hwmon/gpio-fan.c
+++ b/drivers/hwmon/gpio-fan.c
@@ -539,18 +539,7 @@
 	},
 };
 
-static int __init gpio_fan_init(void)
-{
-	return platform_driver_register(&gpio_fan_driver);
-}
-
-static void __exit gpio_fan_exit(void)
-{
-	platform_driver_unregister(&gpio_fan_driver);
-}
-
-module_init(gpio_fan_init);
-module_exit(gpio_fan_exit);
+module_platform_driver(gpio_fan_driver);
 
 MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
 MODULE_DESCRIPTION("GPIO FAN driver");