[U-Boot] buildman rockchip

Hi Simon,

When I'm using the buildman for rockchip platform, it's always build only 20 boards,

and many boards are not build, there are 38 boards with its defconfig in configs/ dir,

could you help to check what's missing?

See build log:

https://travis-ci.org/keveryang/u-boot/jobs/564525467

Thanks,

- Kever