Xylon framebuffer driver

Hi,

Following patches implement Xylon framebuffer driver for logiCVC IP
core device. logiCVC is Configurable Video Controller developed and
optimized for Xilinx FPGA Spartan 6 and Series 7 devices.
Driver is used within Xilinx Linux kernel for ARM by Xylon and Xilinx
Zynq SoC reference designs or custom applications to get fb console or
GUI (Ubuntu desktop, Android) on LCD monitors or embedded device LCDs by
wide number of users accross the world.

Thanks,
Davor