leds: driver for National Semiconductors LP5523 chip

LP5523 chip is nine channel led driver with programmable engines.  Driver
provides support for that chip for direct access via led class or via
programmable engines.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>