net/mlx5: support E-Switch mirroring with modify action

net/mlx5: support E-Switch mirroring with modify action

While there's the modify action and sample action with ratio=1
in the E-Switch flow, and modify action is after the sample
action, means that the modify should only impact on after sample.
MLX5 PMD will monitor the above case and split the E-Switch flow
into two sub flows, similar as sample flow did before:

 - the prefix sub flow with all actions preceding the sample and the
   sample action itself, also append the new jump action after sample
   in the prefix sub flow;
 - the suffix sub flow with the modify action and other actions
   following the sample action.

The flow split as below:

Original flow: items / actions pre / sample / modify / actions sfx
    prefix sub flow -
    items / actions pre / set_tag action / sample / jump
    suffix sub flow -
    tag_item / modify / actions sfx

Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>