If I am not mistaken odroid fits these bills but its uboot and kernel are NOT mainstreamed, AFAIK. Hence not easy to use with CentOS.

You can merge and mix vendor firmware+kernel with a CentOS userland, details are described here [1]. The Armbian people are doing a great job in providing mainlined u-boot and kernel, so this would be my preferred source instead of an outdated BSP image (I still follow the idea to tweak their build system in order to provide a CentOS image). 

Cheers
Uli

[1] https://github.com/umiddelb/aarch64/wiki/Install-CentOS-7-on-your-favourite-ARMv8-ARM64-AArch64-board