Dunno, didn't check, I have no experience with FPGAs yet, and this would have been a lot more work too I think, as the FT2232H handles both USB and SPI for me basically, and flashrom support is also implemented upstream already. I also don't like FPGAs too much as they always force you to use the proprietary, closed-source tools from the FPGA vendors (Xilinx, whatever).
Could be an interesting alternative for the next project maybe.