net/mlx5e: Fix use-after-free when reverting termination table

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix use-after-free when reverting termination table When having multiple dests with termination tables and second one or afterwards fails the driver reverts usage of term tables but doesn't reset the assignment in attr->dests[num_vport_dests].termtbl which case a use-after-free when releasing the rule. Fix by resetting the assignment of termtbl to null.