net/mlx5e: TC, store tc action cookies per attr

The tc parse action phase translates the tc actions to mlx5 flow
attributes data structure that is used during the flow offload phase.
Currently, the flow offload stage instantiates hw counters while
associating them to flow cookie. However, flows with branching
actions are required to associate a hardware counter with its action
cookies.

Store the parsed tc action cookies on the flow attribute.
Use the list of cookies in the next patch to associate a tc action cookie
with its allocated hw counter.

Signed-off-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>