leds: lm3697: Update header block to reflect reality

Currently the headers to be included look rather like a random set.
Update them a bit to reflect the reality.

While at it, drop unneeded dependcy to OF.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>