prepend ovsdb to connection-info for NB connection request

prepend ovsdb to connection-info for NB connection request

for the case when hwvtep features are loaded along side of
ovsdb, the connection-info data is taken from the same base
model, so there is a conflict resulting in an ERROR when
trying to initiate a connection with just "connection-info".
we need to make it more specific, like "ovsdb:connection-info"

Change-Id: I5729a9c1d91507dd3dd6e2cfb8591e916aa6fa88
Signed-off-by: Jamo Luhrsen <jluhrsen@redhat.com>