board: starfive: visionfive2: Order board detection logic to match config

board: starfive: visionfive2: Order board detection logic to match config

Fixup previous merge resolution of this series. Intent is to ease code
readability and logic to match ordering in CONFIG_OF_LIST

- Remove "starfive/" string math
- Remove redundant local cache of calls to get_*_from_eeprom()
- Match name before EEPROM product_id in board_fit_config_name_match()
- Remove single-consumer FDTFILE_* defines
- Do not set fdtfile for visionfive-2-* when unknown model revision

Fixes: 5a0a93a76848 ("Merge branch 'master' of https://source.denx.de/u-boot/custodians/u-boot-riscv")

Signed-off-by: E Shattow <e@freeshell.de>