net/mlx5e: CT: Fix releasing ft entries

Before this commit, on ft flush, ft entries were not removed
from the ct_tuple hashtables. Fix it.

Fixes: ac991b48 ("net/mlx5e: CT: Offload established flows")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Eli Britstein <elibr@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>