ofproto-dpif-xlate: Fix revalidation in execute_controller_action().
If there's no actual packet (e.g. during revalidation),
execute_controller_action() exits right away, without calling
xlate_commit_actions().
xlate_commit_actions() might have an influence on slow_path reason
(which is included in the generated ODP actions), meaning that the
revalidation will not generate the same actions than the original
translation.
Fix the problem by making execute_controller_action() call
xlate_commit_actions() even without a packet.