net/mlx5e: Use shared table for offloaded TC eswitch flows

Currently, each representor netdev use their own hash table to keep
the mapping from TC flow (f->cookie) to the driver offloaded instance.
The table is the one which originally was added for offloading TC NIC
(not eswitch) rules.

This scheme breaks when the core TC code calls us to add the same flow
twice, (e.g under egdev use case) since we don't spot that and offload
a 2nd flow into the HW with the wrong source vport.

As a pre-step to solve that, we move to use a single table which keeps
all offloaded TC eswitch flows. The table is located at the eswitch
uplink representor object.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>