MAINTAINERS: Change LED subsystem git tree URL

This patch removes Bryan Wu from the list of LED subsystem
maintainers and replaces related git tree URL with the one
maintained by Jacek Anaszewski.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Bryan Wu <cooloney@gmail.com>