Use CONFIG_QUANTUM_OVS_BRIDGE_MAPPINGS parameter

The CONFIG_QUANTUM_OVS_BRIDGE_MAPPINGS parameter contains a
comma-separated list of bridge mappings. Since the puppet modules
expects this parameter to be an array, this parameter must be properly
formatted by packstack, then consumed by the puppet module.

Change-Id: Ia09a7185f4a6fc8f5e61ca585e35486fe1520687
Merge "Use CONFIG_QUANTUM_OVS_BRIDGE_MAPPINGS parameter"