Fix in nsx-mode compute node deployment

Moved call plugin_neutronnsx class from cases for controller and compute roles
to common case, because plugin_neutronnsx can handle different roles.

Change-Id: I3907fe9a6fec2e5b802f895ddc7d6c6e35d9a1a3
closes-bug: #1393497
Merge "Fix in nsx-mode compute node deployment"