Fix sending GARP/NA on Bonded Interface Active/Backup Link Up/Down

Fix sending GARP/NA on Bonded Interface Active/Backup Link Up/Down

For bonded interface in Active/Backup mode (mode 1), we need to
send a GARP/NA packet, if IP address is present, on slave link
state change to up or down to help with route convergence. The
callback from DPDK happens in a separate thread so we need to make
sure RPC call is used to signal the send_garp_na process in the
main thread. Also need to fix DPDK polling so the slave links are
not polled.

Change-Id: If5fd8ea2d28c54dd28726ac403ad366386ce9651
Signed-off-by: John Lo <loj@cisco.com>