video: backlight: add ili922x lcd driver

Add LCD driver for Ilitek ILI9221/ILI9222 controller.  The driver uses
SPI interface for controller access and configuration and RGB interface
for graphics data transfer.

Signed-off-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>