Add index to flow_action_entry structure and delete index from police and
gate child structure.

We make this change to offload tc action for driver to identify a tc
action.
Signed-off-by: NBaowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: NSimon Horman <simon.horman@corigine.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>