ofctl_v1_2/3: fix SET_FIELD action and some match fields

this patch fixes the following bugs:

  - "SET_FIELD" action caused an exception at mod_flow_entry command.
  - following match fields caused an exception at get_flow_stats command:
    * mpls_label, arp_spa, arp_tpa
  - following fields in "SET_FIELD" were displayed as classes:
    * eth_dst, eth_src, vlan_vid, mpls_label
  - "arp_spa" and "arp_tpa" were not displayed as IPv4 address

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>