Add initial support for DPDK 21.11

Add initial support for DPDK 21.11

Note that this patch simplistically removes some PROX features, because
they are not directly supported anymore by DPDK, since rte_eth_devices
is now private:
- reading and writing NIC register through PROX command line
- querying ixgbe HW statistics instead of getting them from DPDK

Also adjusted to following DPDK changes:
* struct rte_ether_hdr fields renamed:
  - d_addr -> dst_addr
  - s_addr -> src_addr
* struct rte_eth_rxmode field renamed:
  - max_rx_pkt_len -> mtu
* --master-lcore -> --main-lcore

Signed-off-by: Xavier Simonart <simonartxavier@gmail.com>
Signed-off-by: Patrice Buriez <patrice.buriez@chenapan.org>
Change-Id: I08445b3dd0f7fe471d9bc7cfb557bd3aeb2f50be