drivers/leds: correct __devexit annotations

__devexit functions are discarded without CONFIG_HOTPLUG, so they need
to be referenced carefully.  A __devexit function may also not be called
from a __devinit function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Bryan Wu <bryan.wu@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>