Fix port deletion in NEC Plugin

Cascade on delete from ports.id to packetfitlers.in_port is added
to ensure packet filter entries associated with a port.
Also joined query of packetfilter with port query is added
to avoid additional packetfilter query by port_id.

Fixes: bug #1212102

Change-Id: I8a67649f3361480eda6377b1d8a30bebd18aa714
Merge "Fix port deletion in NEC Plugin"