staging: fbtft: add fb_ili9340 driver

This commit adds the fb_ili9340 driver from the fbtft project at
https://github.com/notro/fbtft

.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Noralf Tronnes <notro@tronnes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>