Enhance nfd-worker placement

[ArangoGutierrez]

What would you like to be added:
enable NFD operator to deploy nfd-worker pods on nodes labeled other than "node-role.kubernetes.io/worker"

Why is this needed:

Current implementation of the NFD-operator create a daemonset which is only taking nodes with "node-role.kubernetes.io/worker" into accout. Kubernetes deployments without this label on non-master nodes won't see nfd-worker scheduled.

[marquiz]

I left this same comment in #31: Do we really need some affinity setting? Daemonset should be scheduled on on every schedulable node, shoudln't it(?)