* helpers/config_loader: Also support bootvar0 eeprom config on Pi4
This allows an eeprom config setting (e.g. BOOTARG0=0x10) to be set on a board
which config.txt can use as a conditional expression (e.g. [bootarg0&0x10]).
* pi5: Write over-voltage config to the UART log
Write the high level over-voltage configuration to the UART log for
diagnostic purposes.
* Stop partition-walk after boot-mode timeout/retries limit
Fix a fatal assert with USB boot where the partition walk could be
retried after the USB timeout/retry limit had been reached.
See: https://github.com/raspberrypi/rpi-eeprom/issues/776
* rpiboot: Extend metadata to report status of operations
Report success/fail status of recovery operations based on config.txt settings
