ethdev: remove DUP action from flow API

ethdev: remove DUP action from flow API

Upcoming changes in relation to the handling of actions list will make the
DUP action redundant as specifying several QUEUE actions will achieve the
same behavior. Besides, no PMD implements this action.

By removing an entry from enum rte_flow_action_type, this patch breaks ABI
compatibility for the following public functions:

- rte_flow_copy()
- rte_flow_create()
- rte_flow_query()
- rte_flow_validate()

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>