net: flow_offload: rename tc_cls_flower_offload to flow_cls_offload

And any other existing fields in this structure that refer to tc.
Specifically:

* tc_cls_flower_offload_flow_rule() to flow_cls_offload_flow_rule().
* TC_CLSFLOWER_* to FLOW_CLS_*.
* tc_cls_common_offload to tc_cls_common_offload.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>