* Add Amber machine
Introduce a new machine for Amber. Store it under Raspberry Pi boards
since Amber is based on the Raspberry Pi Compute Module 4. This way we
can reuse existing scripts.
* Add kernel patches for Amber
Add kernel patches which add a custom device tree for Amber.
* Add device wipe support via GPIO button
Allow to wipe the device by pressing and holding the red button.
* Enable serial console by default
Enable serial console on the on-board USB-to-UART adapter as well as on
the GPIO header.
* Use 64-bit mode by default
Support only 64-bit for Amber, it is mature enough.
