cxgb4: add support for drop and redirect actions

Add support for dropping matched packets in hardware.  Also add support
for re-directing matched packets to a specified port in hardware.

Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>