hwmon: (gpio-fan) Localize platform data

There is not a single user of the platform data header in
<linux/gpio-fan.h>. We can conclude that all current users are
probing from the device tree, so start simplifying the code by
pulling the header into the driver.

Convert "unsigned" to "unsigned int" in the process to make
checkpatch happy.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>