When OVN virtual networks wants to access the provider networks it does
so with the help of a special port type 'localnet'. For the localnet ports
to be present in the agent side, the agent has to carry some details
in the vswitch DB as well a bridge has to be setup for the same.
This patch help to setup up the bridge for provider network mapping and to
add appropriate interfaces to the bridge
Change-Id: Ia6d66fa954571328c0ac3542af17303def382c1a
c3e5717561