Listener Registration for Address Capable Node over-written by Link Change

The variable:
this.addrsNodeListerRegistration

in HostTrackerImpl.java

package: org.opendaylight.l2switch.hosttracker.plugin.internal

is reused to capture the registration of Link change listener.

In the close() method the link change is closed but the address capable node change
is never closed.

This means if the host tracker is disabled the ODL logs get flooded with Exceptions as the dispatcher tries to invoke the data change listener in Host Tracker (for
Address Capable Node) because it was never de-registered.