cxgb4: add tc flower support for L3/L4 rewrite

Adds support to rewrite L3/L4 fields via TC-PEDIT action.
Supported fields for rewrite are:
IPv4 src/dst address, IPv6 src/dst address, TCP/UDP sport/dport.

Also, process match fields first and then process the action items.

Refactor pedit action validation to separate function to avoid
excessive code indentation.

Signed-off-by: Kumar Sanghvi <kumaras@chelsio.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>