The Raspberry Pi firmware cryptography service requires a valid
ECDSA P-256 key instead of a plain random number. Update the usage
instructions for key-provisioning to use this key type as the example.
Update rpi-eeprom-config to support replacement of bootcode.bin
with a customer counter-signed version.
Add a new rpi-sign-bootcode script which enables bootcode.bin
to be counter-signed with the customer key.
N.B. Signed boot on 2712 requires newer firmware which is currently
under development and has not been released.
The tool was removed because for Pi4/Pi400 the VL805 update is now
handled by the bootloader. However, this might still be be useful
for anyone who is developing a custom VL805 board with an SPI EEPROM
and needs a mechanism to flash this.
