net/mlx5: manage header reformat actions with hashed list

net/mlx5: manage header reformat actions with hashed list

To manage encap decap header format actions mlx5 PMD used the single
linked list and lookup and insertion operations took too long times if
there were millions of objects and this impacted the flow
insertion/deletion rate.

In order to optimize the performance the hashed list is engaged. The
list implementation is updated to support non-unique keys with few
collisions.

Signed-off-by: Suanming Mou <suanmingm@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>