* Convert to SDK RP2350A/B determination
Fixes#2878
The SDK uses `defined(PICO_RP2350) && !PICO_RP2350A` to indicate an RP2350B
chip, not the define PICO_RP2350B.
Match the SDK's usage by converting from `defined(PICO_RP2350B)` to
`defined(PICO_RP2350) && !PICO_RP2350A` and update the chip variants
accordingly.
* Need to explicitly override PICO_RP2350A for all
The *SDK*'s board definition file hardcodes a PICO_RP2350A value for
all boards, but we use the same board file for both A and B variants.
Override the SDK board definition in the variant definition file.
* Generic RP2350 needs 2-stage PICO_RP2350A setting
Also ensure SDK board definition included before pins_arduino.h for
clearing up redefinition errors.
* Factor out undef PICO_RP2350A
* Update Arduino.h
* my attempt at adding plasma_2040 support.. cant seem to get it working to test yet though?
* Tracked+replaced files, this now works it seems!
* correct serial count
* Update pins_arduino.h
* Rudimentary Pimoroni Plasma2350 support.
* include correct files + changes needed for proper support.
also!! fixes pin definitions for the i2c on Pimoroni Plasma 2350 (tested, working) and (presumably, untested) on the Plasma RP2040 too by swapping the i2c numbers. i2c now works!!
* use correct USB PID for Plasma 2350
