Closes: #7017
* Remove the 'GP23' alias for CYW1
* Remove the 'CYW0' alias for CYW0
* Switch VBUS_SENSE to CYW2, remove 'GP24' alias
Code that wants to use SMPS_MODE, VBUS_SENSE and LED while being
portable to the W and non-W variants should use those names, not alias
names.
* Remove A3 / VOLTAGE_MONITOR
Right now this cannot be used. The ability to check the voltage monitor
should be added back in some fashion in the future.
This makes all the following work:
* normal microcontroller.reset()
* reset into safe mode or UF2 bootloader via microcontroller.on_next_reset()
* reset into UF2 bootloader via the "1200 baud trick"
The implementation of reset_cpu is from micropython.
The RP2040 is new microcontroller from Raspberry Pi that features
two Cortex M0s and eight PIO state machines that are good for
crunching lots of data. It has 264k RAM and a built in UF2
bootloader too.
Datasheet: https://pico.raspberrypi.org/files/rp2040_datasheet.pdf
