net/mlx5e: TC, CT: Offload ct clear only once

Non-clear CT action causes a flow rule split, while CT clear action
doesn't and is just a header-rewrite to the current flow rule.
But ct offload is done in post_parse and is per ct action instance,
so ct clear offload is parsed multiple times, while its deleted once.

Fix this by post_parsing the ct action only once per flow attribute
(which is per flow rule) by using a offloaded ct_attr flag.

Fixes: 08fe94ec ("net/mlx5e: TC, Remove special handling of CT action")
Signed-off-by: Paul Blakey <paulb@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>