It seems to be the same problem I experienced few days ago --- after rebooting to the new kernel, the ethernet didn't work. It showed up in /sbin/ip, but the link was down and cold dead. I solved it by using
corsair's device tree supplement and rebooting. Networking works fine since then, but I don't know whether it was solved by the efika.forth or by the reboot ^_^.
Unfortunately, I still haven't found a solution to the other problem, which was the biggest reason for updating the DTS: sound. I'll try some more tricks and will eventually make a post about it.