ps2x2pico Version 1.2

Thanks to @seritools for debugging the AMI keyboard controller on 386 boards.

ps2x2pico.uf2 uses the mouse rate set by the host PC
ps2x2pico-100hz.uf2 uses fixed 100 Hz mouse rate, ignores host request
ps2x2pico-200hz.uf2 uses fixed 200 Hz mouse rate, ignores host request