DPDK: fix dpdk_if_get_mtu() callback for the bond interfaces
DPDK: fix dpdk_if_get_mtu() callback for the bond interfaces

Change-Id: I01f1aff2d2a5dad459a061fe28ed7de49716091e
Closes-bug: 1454995

codilime/contrail-vrouter,codilime/contrail-vrouter,codilime/contrail-vrouter,codilime/contrail-vrouter