enic: devcmd for adding IP 5 tuple hardware filters

This patch adds interface to add and delete IP 5 tuple filter. This interface
is used by Accelerated RFS code to steer a flow to corresponding receive
queue.

As of now adaptor supports only ipv4 + tcp/udp packet steering.

Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>