ARM: add an "eet" variant of the imx31_phycore board

The "eet" variant of the imx31_phycore board has an OLED display, using a
s6e63d6 display controller on the first SPI interface, using GPIO57 as a
chip-select for it. With this configuration you can display 256 colour BMP
images in 16-bit RGB (RGB565) LCD mode.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>