leds: add initial driver for AW2016 LED device

Add initial driver for AW2016 LED device
which can support up to 3 LED channels.

Signed-off-by: liweilei <liweilei@awinic.com>
Git-commit: ed6556f262cf7e2086d7728c2f752be4cf94b4d1
Git-repo: https://github.com/awinic-driver/aw2016.git


[huliu@codeaurora.org: move the driver to leds folder
 and make corresponding changes in Kconfig and Makefile,
 also remove the dtsi config file and modify the code
 style.]
Signed-off-by: Hui Liu <huliu@codeaurora.org>
Change-Id: I252ca2710d393ff6dcbb691a2a530433ffbd21e3