net/mlx5e: CT: Use the same counter for both directions

A connection is represented by two 5-tuple entries, one for each direction.
Currently, each direction allocates its own hw counter, which is
inefficient as ct aging is managed per connection.

Share the counter that was allocated for the original direction with the
reverse direction.

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