cxgb4: add tc flower support for ETH-DMAC rewrite

Add support for ETH-DMAC Rewrite via TC-PEDIT action. Also, add
check to assert that vlan/eth-dmac rewrite actions are valid only
in combination with action egress redirect.

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>