net/mlx5e: Parse mirroring action for offloaded TC eswitch flows

Currently, we only support the mirred redirect TC sub-action. In order
to support flow based vport mirroring, add support to parse the mirred
mirror sub-action.

For mirroring, user-space will typically set the action order such that
the mirror port (mirror VF) sees packets as the original port (VF under
mirroring) sent them or as it will receive them.

In the general case, it means that packets are potentially sent to the
mirror port before or after some actions were applied on them. To
properly do that, we should follow on the exact action order as set for
the flow and make sure this will also be the case when we program the HW
offload.

We introduce a counter for the output ports (attr->out_count), which we
increase when parsing each mirred redirect/mirror sub-action and when
dealing with encap.

We introduce a counter (attr->mirror_count) telling us if split is
needed. If no split is needed and mirroring is just multicasting to
vport, the mirror count is zero, all the actions of the TC flow should
apply on that single HW flow.

If split is needed, the mirror count tells where to do the split, all
non-mirred tc actions should apply only after the split.

The mirror count is set while parsing the following actions encap/decap,
header re-write, vlan push/pop.

Signed-off-by: Chris Mi <chrism@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>