nec plugin: allow to delete resource with ERROR status

Previously if a resource is in ERROR status and there is no
corresponding resource on OpenFlow controller, the resource
cannot be deleted through an API request.
This commit rearrange ERROR status check to allow resource
with ERROR status to be deleted.

Closes-Bug: #1295754
Change-Id: I709f5e2066eb5d12ec0f42dff15797acddc2009e
Merge "nec plugin: allow to delete resource with ERROR status"