Add documentation for sysfs interface of adp8860 series backlight
devices by reading through code and git commits.
Signed-off-by: NAishwarya Pant <aishpant@gmail.com>
Acked-by: NMichael Hennerich <michael.hennerich@analog.com>
Acked-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>