Show 802.1q/802.1ah details in the trace output, fixes VPP-111

Show 802.1q/802.1ah details in the trace output, fixes VPP-111

added one line to dpdk-input trace to display vlan tci when PKT_RX_VLAN_PKT flag set
cleaned trace output of af_packet node. Added formatter for vlan_tci.
Merged with John Lo's ethernet trace extension:
Decode both dot1q and dot1ad VLAN tags in ethernet format function
and show what type of vlan tag it is.

dpdk-input & ethernet trace output example of ARP:

00:00:41:545481: dpdk-input
  TenGigabitEthernet8/0/1 rx queue 0
  buffer 0x10f2e: current data 0, length 60, free-list 0, totlen-nifb 0, trace 0x1
  PKT MBUF: port 4, nb_segs 1, pkt_len 60
    buf_len 2176, data_len 60, ol_flags 0x1, data_off 128, phys_addr 0x70e38ac0
    packet_type 0x0
    Packet Offload Flags
      PKT_RX_VLAN_PKT (0x0001) RX packet is a 802.1q VLAN packet ID 100
  ARP: 8c:60:4f:dd:ca:81 -> ff:ff:ff:ff:ff:ff vlan 802.1q id 100
  request, type ethernet/IP4, address size 6/4
  8c:60:4f:dd:ca:81/172.16.110.1 -> ff:ff:ff:ff:ff:ff/172.16.110.10
00:00:41:545492: ethernet-input
  ARP: 8c:60:4f:dd:ca:81 -> ff:ff:ff:ff:ff:ff vlan 802.1q id 100
00:00:41:545499: error-drop
  ethernet-input: unknown vlan

Change-Id: Iae67a945fda4aa2f24032e305a24544dd182b065
Signed-off-by: marek zavodsky <mazavods@gmail.com>