Hi Arvin,
Well I'm no NXP employee so I can't help you with the sources of that demo.
I only tried to help because I maintain i.MX6 support in Buildroot.
Regarding OpenWRT, I guess you just need to update the kernel "recipe" to use the latest 4.1.15 one from NXP. But I won't be able to help you any further, good luck!
Regards,
Gary