Sandbox LCD
===========
This uses the displaymode.txt binding except that only xres and yres are
required properties. Also an additional optional property is defined:
log2-depth: Log base 2 of the U-Boot display buffer depth (4=16bpp, 5=32bpp).
If not provided, a value of 4 is used.
Example:
lcd {
compatible = "sandbox,lcd-sdl";
xres = <800>;
yres = <600>;
log2-depth = <5>;
};