leds: add support for MAX77843 led control driver

Maxim max77843 has 4-channel led controller on max77843 multi
function device. Add max77843 led driver for the device.

Note: this ports below commits in 4.1 kernel in tizen_5.0 branch:
  commit dd11bc28be60 ("mfd: max77843: Add led of_compatible in mfd_cell")
  commit ab013630b285 ("leds: add support for MAX77843 led control driver")

Change-Id: I48c778addba06d1070284e4fc6b8e3ca500c089a
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>