Fix: ITM tunnels going to Unknown state after cic reboot

Fix: ITM tunnels going to Unknown state after cic reboot

As part of cic-1 reboot, DPNs connected to cic-1 got disconnected.
The tunnels associated to those DPNs went to unknown state. Those DPNs
then connected back to cic-3. When cic-3 became entity owner,
EoSListener was not invoked by MDSAL since ITM unregisters the listener
after 1st invocation. So EoSHandler could not set the unknown tunnels to
up. To fix this issue, the listener unregistration is removed.

Change-Id: I96c4f7fc4a94d2eeca8f9ea962a26b900c390493
Signed-off-by: Apurba Mukherjee <apurba.mukherjee@ericsson.com>