fix framebuffer driver

This is my first attempt at any kind of hardware driver, so any criticisms will be well received.

Apparently, the display driver is kind of weird on the EV3. Here are some interesting links I found:
http://elinux.org/images/1/19/Passing_Time_With_SPI_Framebuffer_Driver.pdf
https://github.com/ohporter/linux/commits/st7586fb
https://plus.google.com/+JamesKasper/posts/EtTj24hBao3
https://plus.google.com/108244279740379322507/posts/KfWiuzGRRKx

And the datasheet:
http://pdf1.alldatasheet.com/datasheet-pdf/view/326182/SITRONIX/ST7586S.html

Anyway, I have it working, albeit probably not as efficiently as it could/should be.
![img_20131114_130417_816](https://f.cloud.github.com/assets/963645/1544196/70404a10-4d63-11e3-8928-722d3b1511f0.jpg)