add LCD backlight control HAL

Change-Id: Id2f0ce0b4b4918aa34757ba35c8923e739dc2ee5
Signed-off-by: Max Liao <liaops@embedinfo.com>
Hwcomposer: Fix the problem that ImageWallpaper could not display

Signed-off-by: LiuXin <liuxing@embedinfo.com>

Change-Id: I85df1a94effa28ed6a20d8e4355ab36477fe741a