flow_offload: add skip_hw and skip_sw to control if offload the action

We add skip_hw and skip_sw for user to control if offload the action
to hardware.

We also add in_hw_count for user to indicate if the action is offloaded
to any hardware.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>