netxen: add hardware LRO support

Add support to handle aggregate packets from firmware.
Local TCP flows are automatically identified by firmware
based on the dest IP hash added by driver for local IP
addresses.

The packets are sent down on the jumbo rx ring.

Signed-off-by: Narender Kumar <narender.kumar@qlogic.com>
Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>