Zephyr module for the PicoCalc hardware

This repo is intended to be included via west in order to provide uniform board and shield definitions for the two major halves of a picocalc.

board name picocalc_kb.

Whilst this is commonly called the Keyboard MCU, it's more power management and start-up sequencing than keyboard.

the picocalc_kb board definition has a fairly complete dts for all of the relevant hardware on the picocalc board attached to the F103.

shield name picocalc

This is the half you'd normally care about - it's the bindings for all of the standard interfaces given to the pico.

• Input driver for the standard keyboard firmware
• Work out how to integrate power-control via the keyboard firmware so pmdevice works properly and other power sequencing can work.
• Tidy up picocalc_kb definitions (since I lifted it direct from my WIP PMU/Keyboard firmware.)