Fix Major Sonar Issues: NorthboundEvent.java.

Fixes the following issues:
- 22 Avoid using If/If else/For statements without curly braces

https://sonar.opendaylight.org/component#component=org.opendaylight.ovsdb:openstack.net-virt:master:src/main/java/org/opendaylight/ovsdb/openstack/netvirt/NorthboundEvent.java

Change-Id: I84271baabf37d732fbaf34869b4a60ba697789e8
Signed-off-by: Marcus Koontz <marcus.g.koontz@intel.com>