Basic Proof of Concept Chisel I/O device

[Joeyh021]

Probably just something to blink and LED, or take input from the switches on the board. Got halfway with the seven segment display but I'm fed up of looking at that now.

• [x] Write Chisel
• [x] Write testbenches
• [x] Integrate with existing SoC design I have in vivado
• [x] Test

[Joeyh021]

Done a basic standalone LED blink: https://github.com/Joeyh021/riscv-pio/tree/bef539bf1e6e891c1d9fce9fd97115a51368e7c9

[Joeyh021]

Need to set up a demo of this - will use a basic chisel LED with some registers, then import into vivado and connect to Xilinx's AXI IP