allow empty master if devices found on pod

[sunya-ch]

This PR is an extension of previous PR #153 to prevent the issue when daemon pod has restarted during the job is running and cache has gone.

error:

zero config on cmdDel

As host-device deletion, there is no need of the master name. We add steps to assign the pod device IDs back to response when the daemon has no information of master device names.

after this change:

• daemon return the device IDs with a list of empty master names

return: {[<device ID>] [ ]

• CNI can successfully execute the deletion

Exec DEL net1-0

Signed-off-by: Sunyanan Choochotkaew sunyanan.choochotkaew1@ibm.com