This adds support for the hp680 backlight, as found in the hp6xx series of
sh devices.

Signed-off-by: Andriy Skulysh <askulysh@image.kiev.ua>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>