cxgb4: function namespace cleanup (v3)

Make functions only used in one file local.
Remove lots of dead code, relating to unsupported functions
in mainline driver like RSS, IPv6, and TCP offload.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Dimitris Michailidis <dm@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>