Add Xylon logiCVC framebuffer driver

Hello,

I am sending the patch series to add support for Xylon logiCVC IP core device.
logiCVC is Configurable Video Controller developed and optimized for Xilinx 
FPGA devices.
Driver has been compiled and tested with kernel 3.18 on Zynq SoC, running fb
console and other graphics on single or multiple LCDs.

Kind regards,
Davor