layer: Change references from dunfell to hardknott
In layer.conf, the ci and the README, use hardknott as default branch. Disable dhcp append file, as the dhcp package has been replaced.
BCS 746-000293
In layer.conf, the ci and the README, use hardknott as default branch. Disable dhcp append file, as the dhcp package has been replaced.
BCS 746-000293