NEC plugin: Allow to apply Packet filter on OFC router interface

Config parameter support_packet_filter_on_ofc_router is added
only to make the pluign work with the old version of PFC v5
which has no support of packet filter on vrouter interface.

Closes-Bug: #1384263
Change-Id: I2f54419e0b7c84c554ab2039ebaebdb065f9e502
Merge "NEC plugin: Allow to apply Packet filter on OFC router interface"