Thanks @jsoriano for reply. Made some changes as per below and it is working.
hosts: ["https://${HOSTNAME}:10250"]
bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
ssl:
# disable verification since kubelete uses self signed certificate
verification_mode: none
certificate_authorities:
- /var/run/secrets/kubernetes.io/serviceaccount/ca.crt