解决答案在第二步骤,csdn转载来转载去的早已失效。见:https://mirrors.tuna.tsinghua.edu.cn/help/git-repo/
Rockchip Debian SDK说明
1、安装repo:sudo apt-get install repo或者按提示:sudo apt-get install phablet-tools
2、修改repo:sudo vim /usr/bin/repo:REPO_URL=’https://mirrors.tuna.tsinghua.edu.cn/git/git-repo/’
2、repo init -u https://github.com/rockchip-linux/manifests
3、repo sync