Fix the cleaning of EVPN tor NH.
Also set the subnet flag in path of subnet route. This path is where discard NH is added i.e. local peer

https://bugs.launchpad.net/juniperopenstack/+bug/1372780

Change-Id: If84b6f5cd133d6e4aee5dfbeab780e897a0e8e4f
Merge "Fix the cleaning of EVPN tor NH. Also set the subnet flag in path of subnet route. This path is where discard NH is added i.e. local peer"