leds: leds-lp5523: modify the way of setting led device name

Currently all leds channels begins with string lp5523.  Patch adds a
possibility to provide name via platform data.  This makes it possible to
have several chips without overlapping sysfs names.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: Arun Murthy <arun.murthy@stericsson.com>
Cc: Ilkka Koskinen <ilkka.koskinen@nokia.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>