Bump kernel version & use universal RPI platform

This basically allows the system to boot on a variety of raspberry pi boards, including RPI 3b+ (I have the board here, but I have no HDMI cable to test) and pushes us towards reterminal support. We need to merge this now as firmware was upgraded upstream(https://gitlab.com/nonguix/nonguix/-/merge_requests/187) This PR also includes reterminal kernel modules (disabled by default).