drivers: implements lcd interface for ili9341

This implements the lcd interface to displaying data on the lcd display powered
by the ili9341 lcd driver.

This driver implements all methods defined in the lcd_dev_s structure except
getcontrast and setcontrast. They are not supported by the hardware.

Furthermore the driver allows to use multiple displays powered by the ili9342 IC
with only one driver instance. So it is theoretically possible to support more
than one connected ili9341 lcd display. The displays can be configured
independently. Currently two lcd devices supported. This should be enough for
now. Read the corresponding code section of how to add more devices if
neccessary.

The following settings are configurable:

1. Pixel format
   Define the pixel format of the connected display. Currently only
   RGB-565 supported.

2. Orientation
   Define the orientation of the display. This can be portrait or
   landscape and reversed values.

1. Write only
   The driver allows to disable any getrun method if not neccessary to
   reduce code size. This is done by enable CONFIG_LCD_NOGETRUN in the nuttx
   configuration.

Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>