梳理下hg255d完美刷op的步骤

 Post  97  1 
  1. 原版uboot下刷1102-0x20000_hg255d-squashfs-tftp.checksum2
  2. 备份本机eeprom：cat /dev/mtd2 >/tmp/eeprom.bin
  3. TTL更换uboot
  4. 刷op固件和之前备份的eeprom
  5. 完成