Ensure you have go 1.9.2 (or better) environment set up. Also make sure GOROOT, GOPATH and PATH environment variables are set to their appropriate values.

For example on CentOS 7 or Ubuntu 16 add the following lines to your .bashrc

export GOROOT="/usr/lib/go-1.9"
export GOPATH="$HOME/go"
export PATH="$PATH:$GOROOT/bin:$GOPATH/bin"

$ make code-gen
./hack/update-codegen.sh