app/testpmd: update flow director commands

app/testpmd: update flow director commands

Add new command to set flow director's mask:
  - flow_director_mask
Update arguments of commands:
  - flow_director_filter
  - flow_director_flex_mask
  - flow_director_flex_payload
Following commands of flow director filter are removed:
  - add_signature_filter
  - upd_signature_filter
  - rm_signature_filter
  - add_perfect_filter
  - upd_perfect_filter
  - rm_perfect_filter
  - set_masks_filter
  - set_ipv6_masks_filter

Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>