wirehosts: Always cast node num to int
wirehosts: Always cast node num to int

Recent change in infrared caused that 'num' of given node is no longer
an int type but string. This patch makes sure we use num as in whenever
needed.

Change-Id: I74dd2f7d1c0c0ad0ada6af12b1c3a82f7ecb3846

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared