msm:camera: Add support for LED flash as i2c node

Add LED flash driver for adp1660 as i2c node.
Create v4l2 node and add control logic for i2c
LED Flash driver.

Change-Id: Iccdd341c280e58dfa5b374d06b16c2d9d344f748
Signed-off-by: Lokesh Kumar Aakulu <lkumar@codeaurora.org>