drivers/leds/leds-pca9633.c: remove unused 'adapter' variable

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Peter Meerwald <p.meerwald@bct-electronic.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>