ethdev: fix C99 flexible arrays from flow API

ethdev: fix C99 flexible arrays from flow API

This patch replaces C99-style flexible arrays in struct rte_flow_action_rss
and struct rte_flow_item_raw with standard pointers to the same data.

They proved difficult to use in the field (e.g. no possibility of static
initialization) and unsuitable for C++ applications.

Affected PMDs and examples are updated accordingly.

This breaks ABI compatibility for the following public functions:

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

Fixes: b1a4b4cbc0a8 ("ethdev: introduce generic flow API")

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>