net/mlx5e: TC, Pass attr to tc_act can_offload()

In later commit we are going to instantiate multiple attr instances
for flow instead of single attr.
Make sure the parsing using correct attr and not flow->attr.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>