ethdev: allow action with any config object type

ethdev: allow action with any config object type

In current implementation, an action which requires parameters
must accept them enclosed in a structure.
Some actions require a single, trivial type parameter, but it still
must be enclosed in a structure.
This obligation results in multiple, action-specific structures, each
containing a single trivial type parameter.

This patch introduces a new approach, allowing an action configuration
object of any type, trivial or a structure.

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