Init data-broker before topo-provider registration to prevent NPE
java.lang.NullPointerException: null
at org.opendaylight.bgpcep.bgp.topology.provider.AbstractTopologyBuilder.initTransactionChain(AbstractTopologyBuilder.java:292)
at org.opendaylight.bgpcep.bgp.topology.provider.AbstractTopologyBuilder.start(AbstractTopologyBuilder.java:107)
at org.opendaylight.bgpcep.bgp.topology.provider.config.TopologyReferenceSingletonServiceImpl.instantiateServiceInstance(TopologyReferenceSingletonServiceImpl.java:51)
. . .
JIRA: BGPCEP-870
Change-Id: Iaec5a537cb5125e1355f197222d9265673d779a9
Signed-off-by: Ajay Lele <ajayslele@gmail.com>