net/mlx5: add OS specific flow actions operations

net/mlx5: add OS specific flow actions operations

This patch introduces the OS specific functions, for flow actions
create and destroy operations.

In existing implementation, the functions to create flow actions
return a pointer to the created action object.

The new OS specific functions to create flow actions return 0 on
success, and (-1) on failure.
On success, a pointer to the created action object is returned
using an additional parameter.
On failure errno is set.

Signed-off-by: Dekel Peled <dekelp@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>