Add support for FATSOv2 to the driver. FATSOv2 offloads far more of the task
of TCP segmentation to the firmware, such that we now just pass a single
super-packet to the NIC. This means TSO has a great deal in common with a
normal DMA transmit, apart from adding a couple of option descriptors.
NIC-specific checks have been moved off the fast path and in to
initialisation where possible.
This also moves FATSOv1/SWTSO to a new file (tx_tso.c). The end of transmit
and some error handling is now outside TSO, since it is common with other
code.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
