examples/l3fwd: print device name when adding routes

examples/l3fwd: print device name when adding routes

Since the number of Ethernet ports have gone up, print the device name
(which for PCI devices is the BDF triplet), along with the routes.
This is also helpful for cases where allow listing order is not honored.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Reviewed-by: Conor Walsh <conor.walsh@intel.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>