Update pico-sdk to 1.1.2
Add methods to block the opposite core while doing flash updates.
Ensure opposite core is stopped in LittleFS and EEPROM while doing
flash updates.
Update documentation with new calls.
The SDK would assert if a flash write/erase happened past the end of the
flash space it was built with. So, 8MB chips would crash when accessing
offset 3MB, for example.
Avoid this by specifying the maximum flash available so the SDK won't
trip.
Fixes#76
Build all 4 different boot_stage2 objects with SPI/2 and SPI/4 options.
Add a menu to the generic board to allow selecting between them.
Use the potato/4 boot2 for the Adafruit Feather until we have a better
version verified.
Fixes#42
Add support for Adafruit Feather RP2040 (8MB). Identified with a unique
USB PID so it displays properly once programmed one time. Moved LED to
pin 13 (per the website docs), but have no board to test.
Add over/underclocking menus, applied at boot. Use at your own risk, as
usual.
Add shims to allocate flash space for a filesystem (but not implemented
yet).
Add a "generic" RP2040 board
Earle F. Philhower, III