net/mlx5: enhance flow dump

net/mlx5: enhance flow dump

Multiple rules could use the same encap_decap/modify_hdr/counter action.
The flow dump data could be duplicated.

To avoid redundancy, flow dump value is based on the actions' pointer
instead of previous rules' pointer.

For counter, the data is stored in cmng of priv->sh.
For encap_decap/modify_hdr, the data stored in encaps_decaps/modify_cmds.
Traverse the fields and get action's pointer and information.

Formats are same for information in the dump except "id" stands for
actions' pointer:
    Counter:     rec_type,id,hits,bytes
    Modify_hdr:  rec_type,id,actions_number,actions
    Encap_decap: rec_type,id,buf

Signed-off-by: Haifei Luo <haifeil@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>