Add PID 1209:C64C for Pico64 Keyboard - #1325

Requesting PID 0xC64C for Pico64 Keyboard: https://github.com/do2mad/pico64-keyboard

• Open-source firmware, MIT license (LICENSE file in the repository)
• Runs on a stock Raspberry Pi Pico 2 W, hand-wired to the C64 keyboard connector (wiring diagram in docs/);
  an optional adapter PCB is published as Gerber files (CC BY-NC-SA, see LICENSE-HARDWARE.md) -
  the PID is requested for the open-source firmware
• USB classes: HID boot keyboard + CDC ACM (serial console), composite device
• Currently uses the test PID 1209:0001, will switch to the assigned PID

Thank you!